Search

The end-Permian mass extinction (252.3 Ma) was an abrupt and severe loss of diversity on land and in the oceans, the largest extinction of the Phanerozoic. Recent palaeontological, geochemical and modelling studies link the extinction with eruption of the Siberian Traps flood basalts, which would have caused global warming, ocean acidification and shallow-marine anoxia. On land, global warming and aridification were mostly responsible for the vertebrate and plant extinction. Although almost no marine group emerged unscathed, selectivity favoured more active animals, whereas sessile and heavily calcified taxa such as corals and reef-building sponges suffered heavily. The recovery interval was unusually long, likely because of continuing stress, and the extinction resulted in permanent shifts in marine ecosystem composition and structure, giving rise to the mollusc-rich communities that still dominate today. Key Concepts: The end-Permian mass extinction was a severe crisis for nearly every plant and animal group, on land and in the oceans. The extinction was abrupt, apparently synchronous on land and in the sea, with the majority of taxonomic losses occurring over a few tens of thousands of years, approximately 252.3 Ma. In the marine realm, more actively motile animal groups fared relatively better during the extinction. Although low-oxygen waters were widespread and contributed to the marine extinction, the primary cause most likely was global warming and ocean acidification from CO2 released by Siberia Traps flood basalt volcanism. The terrestrial extinction was also caused by global warming and, among plants, the resulting dry conditions. It took an unusually long time (5–7 million years) for most marine and terrestrial ecosystems to recover from the extinction, likely because of continuing intermittent stress. The extinction triggered permanent changes in the composition and structure of marine ecosystems, giving rise to mollusc-dominated communities that remain dominant today. Keywords: Permian; Triassic; extinction; ocean acidification; climate change; reefs; evolution

How many species face extinction due to climate change? This is one of the most pressing questions of climate change biology. It is featured in front-page stories and on the evening news. “More than a million species wiped out by climate change” and “One third of all of the world's plants and animals gone due to climate change” are examples of some of the headlines. What is the science behind these sensational claims, and how do we know whether climate change poses a major extinction risk? This chapter provides answers to these questions.

There are few global challenges as widespread, as complex, as significant to our future, and politically as controversial as that of global warming. The goal of this chapter is, in essence, to motivate this textbook; to convince you, the reader, that very nearly all of the topics in this text need to be understood in order to grasp the subtleties of a subject such as global warming.

Protecting biodiversity against the impacts of climate change requires effective conservation strategies that safeguard species at risk of extinction1. Microrefugia allowed populations to survive adverse climatic conditions in the past2,3, but their potential to reduce extinction risk from anthropogenic warming is poorly understood3,4,5, hindering our capacity to develop robust in situ measures to adapt conservation to climate change6. Here, we show that microclimatic heterogeneity has strongly buffered species against regional extirpations linked to recent climate change. Using more than five million distribution records for 430 climate-threatened and range-declining species, population losses across England are found to be reduced in areas where topography generated greater variation in the microclimate. The buffering effect of topographic microclimates was strongest for those species adversely affected by warming and in areas that experienced the highest levels of warming: in such conditions, extirpation risk was reduced by 22% for plants and by 9% for insects. Our results indicate the critical role of topographic variation in creating microrefugia, and provide empirical evidence that microclimatic heterogeneity can substantially reduce extinction risk from climate change., The work was funded by Natural England and by NERC grant NE/L00268X/1 to R.J.W. and I.M.D.M.

We used daily maximum temperature data (1986–2100) from the COSMO-CLM (COnsortium for Small-scale MOdeling in CLimate Mode) regional climate model and the population statistics for China in 2010 to determine the frequency, intensity, coverage, and population exposure of extreme maximum temperature events (EMTEs) with the intensity–area–duration method. Between 1986 and 2005 (reference period), the frequency, intensity, and coverage of EMTEs are 1330–1680 times yr–1, 31.4–33.3°C, and 1.76–3.88 million km2, respectively. The center of the most severe EMTEs is located in central China and 179.5–392.8 million people are exposed to EMTEs annually. Relative to 1986–2005, the frequency, intensity, and coverage of EMTEs increase by 1.13–6.84, 0.32–1.50, and 15.98%–30.68%, respectively, under 1.5°C warming; under 2.0°C warming, the increases are 1.73–12.48, 0.64–2.76, and 31.96%–50.00%, respectively. It is possible that both the intensity and coverage of future EMTEs could exceed the most severe EMTEs currently observed. Two new centers of EMTEs are projected to develop under 1.5°C warming, one in North China and the other in Southwest China. Under 2.0°C warming, a fourth EMTE center is projected to develop in Northwest China. Under 1.5 and 2.0°C warming, population exposure is projected to increase by 23.2%–39.2% and 26.6%–48%, respectively. From a regional perspective, population exposure is expected to increase most rapidly in Southwest China. A greater proportion of the population in North, Northeast, and Northwest China will be exposed to EMTEs under 2.0°C warming. The results show that a warming world will lead to increases in the intensity, frequency, and coverage of EMTEs. Warming of 2.0°C will lead to both more severe EMTEs and the exposure of more people to EMTEs. Given the probability of the increased occurrence of more severe EMTEs than in the past, it is vitally important to China that the global temperature increase is limited within 1.5°C.

The existence and magnitude of the recently suggested global warming hiatus, or slowdown, have been strongly debated1–3. Although various physical processes4–8 have been examined to elucidate this phenomenon, the accuracy and completeness of observational data that comprise global average surface air temperature (SAT) datasets is a concern9,10. In particular, these datasets lack either complete geographic coverage or in situ observations over the Arctic, owing to the sparse observational network in this area 9 . As a consequence, the contribution of Arctic warming to global SAT changes may have been underestimated, leading to an uncertainty in the hiatus debate. Here, we constructed a new Arctic SAT dataset using the most recently updated global SATs 2 and a drifting buoys based Arctic SAT dataset 11 through employing the ‘data interpolating empirical orthogonal functions’ method 12 . Our estimate of global SAT rate of increase is around 0.112 °C per decade, instead of 0.05 °C per decade from IPCC AR5 1 , for 1998–2012. Analysis of this dataset shows that the amplified Arctic warming over the past decade has significantly contributed to a continual global warming trend, rather than a hiatus or slowdown. The Arctic is under-represented in surface temperature datasets and this could affect estimates of global warming. A new dataset with greater coverage of the Arctic shows a higher warming rate of 0.112 °C per decade compared to 0.005 °C from IPCC AR5.

The rapid Indian Ocean warming during the early-21th century was a major heat sink for the recent global surface warming slowdown. Analysis of observational data and ocean model experiments reveals that during 2003–2012 more than half of the increased upper Indian Ocean heat content was concentrated in the southeast Indian Ocean (SEIO), causing a warming “hot spot” of 0.8–1.2 K decade−1 near the west coast of Australia. This SEIO warming was primarily induced by the enhancements of the Pacific trade winds and Indonesian throughflow associated with the Interdecadal Pacific Oscillation's (IPO) transition to its negative phase, and to a lesser degree by local atmospheric forcing within the Indian Ocean. Large-ensemble climate model simulations suggest that this warming event was likely also exacerbated by anthropogenic forcing and thus unprecedentedly strong as compared to previous IPO transition periods. Climate model projections suggest an increasing possibility of such strong decadal warming in future.

Based on outputs from regional climate model COSMO-CLM (CCLM), climate conditions in the Haihe River Basin (HRB) under the 1.5 and 2.0 °C global warming scenarios were projected. Drought characteristics were analyzed by the Standardized Precipitation Evapotranspiration Index (SPEI), and population exposure to regional droughts in the warming world were then assessed by a combination of the population in 2010. It was revealed that both annual precipitation and potential evapotranspiration will increase in the 1.5 °C warming level relative to the reference period of 1986–2005 in the HRB. But annual precipitation was projected to decrease in the 2.0 °C warming level, although potential evapotranspiration was projected to increase. The temperature in the HRB was projected to rise faster than the global mean, and the timing of the regional 2.0 °C warming level will come earlier. Under the global warming of 1.5 °C, intensity and coverage of droughts in the HRB exhibit no significant trends relative to 1986–2005, while the drought frequency might decrease to a certain degree. Under the global warming of 2.0 °C, intensity and coverage of droughts will increase notably. In particular, drought coverage in the 2.0 °C level will be 1.9 times larger than that of the 1.5 °C scenario. Drought frequency under the 2.0 °C warming scenario will increase relative to the 1.5 °C warming scenario but still be less than that of the reference period. As a result, population exposure to droughts in the 1.5 °C warming level could be reduced by 30.4% relative to the 1986–2005 period, but increase by 74.8% in the 2.0 °C warming level. Seasonally, an increasing trend of exposure to severe droughts in summer, autumn and winter was projected in the 1.5 °C global warming level, while that to extreme droughts in summer and winter will decrease. Under 2.0 °C global warming scenario, increasing trend of severe and extreme droughts was projected in spring, autumn and winter. And the exposure to extreme droughts in autumn and winter might be doubled relative to the reference period. Similar spatial distribution patterns were found for population exposure in 1.5 °C and 2 °C global warming levels with high values projected in south and central basin but low in north and west. But the difference is, less population will be exposed to droughts in most area of HRB under 1.5 °C warming scenario, while population exposure will be larger under 2.0 °C global warming scenario relative to 1986–2005. The additional 0.5 °C from 1.5 °C to 2.0 °C will obviously increase the drought risks, especially in the southern and central HRB. Considering the projections that more drought risks might exist under the 2.0 °C warming scenario than in the 1.5 °C level, a perspective to keep the increase in global mean temperature below 2.0 °C and limit it to 1.5 °C, has far-reaching implications to socioeconomic development in the HRB.

The planet is warming; however, this includes periods of accelerated and slowed warming. Although the tropical Pacific played a role in the recent slowdown, this study shows sea surface temperatures across multiple basins influence the rate of warming.

Limiting average global warming to 2 °C will not limit regional warming to the same levels. This study shows drylands have warmed, and will continue to warm, more than the humid lands that are primarily responsible for emissions. The Paris Agreement aims to limit global mean surface warming to less than 2 °C relative to pre-industrial levels1,2,3. However, we show this target is acceptable only for humid lands, whereas drylands will bear greater warming risks. Over the past century, surface warming over global drylands (1.2–1.3 °C) has been 20–40% higher than that over humid lands (0.8–1.0 °C), while anthropogenic CO2 emissions generated from drylands (∼230 Gt) have been only ∼30% of those generated from humid lands (∼750 Gt). For the twenty-first century, warming of 3.2–4.0 °C (2.4–2.6 °C) over drylands (humid lands) could occur when global warming reaches 2.0 °C, indicating ∼44% more warming over drylands than humid lands. Decreased maize yields and runoff, increased long-lasting drought and more favourable conditions for malaria transmission are greatest over drylands if global warming were to rise from 1.5 °C to 2.0 °C. Our analyses indicate that ∼38% of the world’s population living in drylands would suffer the effects of climate change due to emissions primarily from humid lands. If the 1.5 °C warming limit were attained, the mean warming over drylands could be within 3.0 °C; therefore it is necessary to keep global warming within 1.5 °C to prevent disastrous effects over drylands.

Global climate model simulations project that the tropical Andes Mountains of South America, which are particularly vulnerable to climate change because of a reliance on snow and glacial melt for freshwater resources, will experience enhanced warming in the near future, with both higher rates of warming at higher elevations within the mountain range itself and localized enhancement of warming exceeding surrounding areas of the globe. Yet recent surface temperature changes in the tropical Andes do not show evidence for either elevation-dependent warming or regional enhancement of warming on average. However, it remains a possibility that the expected warming trends in this region have begun to manifest in other ways (e.g., in the free atmosphere or at intermediate mountain elevations). This paper proposes evidence from several reanalysis products that there has indeed been a regional enhancement of midtropospheric warming around the central Andes over the past few decades that makes this region stand out as a hot spot within the broader pantropics. This trend is generally not reproduced by historical AMIP climate model simulations, which suggests that the mechanisms through which the atmosphere is warming over the central Andes are not adequately captured by climate models. Possible explanations for localized enhancement of warming in this region are considered. On the other hand, reanalysis products do not consistently exhibit enhanced warming at intermediate mountain elevations in the central Andes as evidenced by the generally moderate rates of change in the freezing-level height, except perhaps in the highest-resolution reanalysis product.

There has been an increasing number of studies on species extinction because of global warming based on estimations of changes in species distributions. Life cycle impact assessment methods do not have a biodiversity damage factor for global warming that uses the extinction risk index. In this study, a method for determining the extinction risks of individual species per unit CO2 emission was proposed and test calculations of the extinction risks of 216 species of Japanese vascular plants were performed. We also examined the possibility of determining local and global extinction risk factors using this method. This method uses the Expected Increase in the Number of Extinction Species (EINES), which is defined as the inverse of the time to extinction, as the extinction risk index. Procedures for determining the extinction risks of individual species per unit CO2 emission (EINES/species/kg) are as follows. First, based on the base scenario of CO2 emission, a niche-based species distribution model is used to estimate species distribution areas in 2000 and 2100 and calculate the distribution area decrease over 100 years. The number of years before the zero distribution area is then determined by assuming that the decrease is constant. Extinction risk is defined as the inverse of this time. The final step is to determine the extinction risk at specific CO2 emissions in addition to the base emission scenario and divide the difference in the extinction risk by the additional amount of CO2 emissions. The distribution areas of 216 species of Japanese vascular plants having southern distribution limits were estimated to decrease by 40–85% in 100 years. The accuracy of the estimation was sufficient according to the value of area under the curve (AUC). Considering climate models and migration conditions, the extinction risk per unit CO2 emission was estimated between −0.6 × 10−18 and 4.7 × 10−18 (EINES/species/kg). We converted the normalization values of the extinction risk of Japan for the 216 species to compare impact of land use changes and waste processing with that of global warming on the species. We found that global warming has smaller impact compared with land use changes and larger impact compared with waste processing. A method for estimating the extinction risks of species per unit CO2 emission was proposed, and it can be used to determine the local and global extinction risk factors of CO2.

The high rate of anthropogenic climate change projected for coming decades and evidence of low migration ability for many species have led researchers to warn of a looming extinction crisis. This threat is expected to be most acute for small-ranged endemic species, which could see novel climatic conditions develop rapidly across the entirety of their limited geographic ranges. To avoid extinctions, some conservationists have proposed that climate-imperiled species might be candidates for “assisted colonization” or “managed relocation” to new regions, outside their historical ranges. One major concern related to managed relocation is the possibility that some relocated species could later become problematic invasives where they are introduced. In this review, we consider how these emerging conservation challenges might unfold for the flora of New England. A range of evidence suggests that most plant species native to New England might be resilient to immediate extinction risk from climate change, ...

The perception of the accuracy of regional climate projections made in the early 1990s about climate change by 2030 may be influenced by how the temperature trend has changed in the 25 years since their publication. However, temperature trends over this period were influenced not only by external forcings such as greenhouse gases but also natural variations. The temperature of Southern Australia, the Sahel, South Asia and Southern Europe are currently within the warming estimates from statements in the early 1990s from the IPCC and CSIRO, assuming a linear trend between 1990 and 2030. However, northern Australia and central North America are currently at the lower limit or below these projections, having featured areas of multi-year regional cooling during global warming, sometimes called ‘warming holes’. Recent climate model simulations suggest that cooling can be expected in the recent past and near future in some regions, including in Australia and the US, and that cooling is less likely over 1990–2030 than in 1990–2015, bringing observations closer to the IPCC and CSIRO warming estimates by 2030. Cooling at the 25-year scale in some regions can be associated with cyclic variability such as the Inter-decadal Pacific Oscillation, or low trend such as in the Southern Ocean. Explicitly communicating the variability in regional warming rates in climate projections, including the possibility of regional warming ‘holes’ (or the opposite of ‘surges’ or ‘peaks’) would help to set more reliable expectations by users of those projections.

Explanations for the industrial epoch warming are polarized around the hypotheses of anthropogenic warming (AW) and giant natural fluctuations (GNFs). While climate sceptics have systematically attacked AW, up until now they have only invoked GNFs. This has now changed with the publication by D. Keenan of a sample of 1000 series from stochastic processes purporting to emulate the global annual temperature since 1880. While Keenan's objective was to criticize the International Panel on Climate Change's trend uncertainty analysis (their assumption that residuals are only weakly correlated), for the first time it is possible to compare a stochastic GNF model with real data. Using Haar fluctuations, probability distributions, and other techniques of time series analysis, we show that his model has unrealistically strong low-frequency variability so that even mild extrapolations imply ice ages every ≈1000 years. Helped by statistics, the GNF model can easily be scientifically rejected.

Global mean surface temperature change over the past 120 years resembles a rising staircase. Simulations with a coupled ocean–atmosphere model reveal that the tropical Pacific Ocean is the pacemaker of variable warming rates.

Predicting the responses of organisms is a complex challenge especially when water temperature is expected to increase over the coming decades, as a result of global warming. In this work the effects of warming on phytoplankton communities were investigated. An indoor experiment was performed, where water from a Mediterranean lagoon was incubated at different temperatures. Three treatments were applied in triplicate incubation units: the control (11 °C), 3 °C increase (14 °C), and 6 °C increase (17 °C). Our results showed significant effects by warming on phytoplankton. The abundance of relatively smaller taxa (Chlorella sp. and Planktothrix agardhii–rubescens group) increased at 17 °C, whereas the abundance of relatively larger species (Cyclotella sp. and Thalassiosira sp.) decreased, compared with the control. This shift towards smaller taxa resulted in a higher total biomass but lower chlorophyll a concentrations at the highest temperature.

The contribution of urbanization to warming in China has been difficult to quantify owing to the proximity of rural stations to urban areas. A novel detection and attribution analysis separates the contribution of all external forcings, and shows that urbanization accounts for about one-third (0.5 °C) of the total warming signal in China (1.4 °C).

A new generation of an Earth system model now includes a number of land-surface processes directly relevant to analyzing potential impacts of climate change. This model, HadGEM2-ES, allows us to assess the impacts of climate change, multiple interactions, and feedbacks as the model is run. This paper discusses the results of century-scale HadGEM2-ES simulations from an impacts perspective – specifically, terrestrial ecosystems and water resources – for four different scenarios following the representative concentration pathways (RCPs), used in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2013, 2014). Over the 21st century, simulated changes in global and continental-scale terrestrial ecosystems due to climate change appear to be very similar in all 4 RCPs, even though the level of global warming by the end of the 21st century ranges from 2 °C in the lowest scenario to 5.5° in the highest. A warming climate generally favours broadleaf trees over needleleaf, needleleaf trees over shrubs, and shrubs over herbaceous vegetation, resulting in a poleward shift of temperate and boreal forests and woody tundra in all scenarios. Although climate related changes are slightly larger in scenarios of greater warming, the largest differences between scenarios arise at regional scales as a consequence of different patterns of anthropogenic land cover change. In the model, the scenario with the lowest global warming results in the most extensive decline in tropical forest cover due to a large expansion of agriculture. Under all four RCPs, fire potential could increase across extensive land areas, particularly tropical and sub-tropical latitudes. River outflows are simulated to increase with higher levels of CO2 and global warming in all projections, with outflow increasing with mean temperature at the end of the 21st century at the global scale and in North America, Asia, and Africa. In South America, Europe, and Australia, the relationship with climate warming and CO2 rise is less clear, probably as a result of land cover change exerting a dominant effect in those regions.

Closure of the Earth’s energy budget relies on strong aerosol cooling since 1998, if the same feedbacks apply for anthropogenic and natural variability. An analysis of climate model simulations suggests that these feedbacks are instead distinct.

The mass extinction event that occurred at the close of the Permian Period (~ 252 million years ago) represents the most severe biodiversity loss in the ocean of the Phanerozoic. The links between the global carbon cycle, climate change and mass extinction are complex and involve a whole range of often inter-related geochemical, biological, ecologic and climatic factors. It has become widely accepted that the end-Permian mass extinction was associated with a global warming event, because the age of the Siberian Trap eruption, a potentially massive source of carbon dioxide, coincides within error with the extinction event. However, geologic data that are in support of this global warming event are relatively sparse. The chain of events and the causal relationship between the eruption of Siberian Traps and mass extinction is not well established. Global warming, in particular, has only been reported from limited proxy data and climate models, for which the pCO2 in the atmosphere just before and during the end-Permian extinction event is poorly known. This study critically assesses both the proxy climate data and the existing paleoclimate simulations with the goals of assessing our current understanding of the link between mass extinction and climate change and providing some guidance for future studies. Proxies indicate that prior to the end-Permian extinction event tropical sea surface temperatures ranged from ~ 22 to 25 °C, and possible pCO2 values ranged from ~ 500 to ~ 4000 ppm before the extinction event. During the peak extinction, tropical temperatures rose up to ~ 30 °C while pCO2 perhaps increased up to ~ 8000 ppm. Climate models that use different pre-event pCO2 values show similar amount of CO2 doubling to replicate the observed carbon isotope excursions. We find that the temperature anomaly during the end-Permian extinction is consistent with ~ 1.5 doublings of atmospheric pCO2, and that the implied climate sensitivity is 5–6 °C, within the upper range of values produced by climate models.

Climate change is an important factor affecting species dispersal and distribution through time and the accelerated global warming has currently concerned decision makers and conservationists. Because protected areas are spatially static, species extinction risk is generally expected to increase under climate change scenarios as a consequence of range shift and decrease. This study aims to understand the current conservation status of Actinote quadra, a neotropical threatened butterfly species, as well as predict how it will be in the future. By coupling ecological niche modeling and climatic simulations, we predicted the species distribution in different future global warming scenarios (2050 and 2070) and estimated the proportion of species range overlapping protected areas through time. Our findings showed a generalized decrease of the potential distribution of A. quadra in the end of 21st century, with the most prominent range loss predicted to occur out of protected areas. Although climate change will potentially drive A. quadra into reserves, the predicted range collapse would be enough to increase its extinction risk from vulnerable, like currently categorized, to the status of critically endangered in accordance to IUCN red list criteria. Taking into account the fragmented and discontinuous landscapes across the Atlantic Forest's hotspot, we propose a conservation strategy for A. quadra based on potential ecological corridors linking climatically suitable areas and discuss the need for amplifying and connecting the current protected areas to maintain this threatened species at longer time under a global warming scenario.

Small Island Developing States in the tropical western Pacific are among the most vulnerable to climate change. While a great deal of information on the observed climate change trends and their cause is available for many other regions and for the globe as a whole, much less information has been available specifically for the Pacific. Here, we show that warming over the past 50 years in the western Pacific is evident in recently homogenized tropical station data, and in gridded surface temperature data sets for the region. The warming has already emerged from the background climate variability. The observational data and Coupled Model Intercomparison Project Phase 5 climate model output are used to show that the observed warming was primarily caused by human-forced changes to the earth's radiative balance. Further warming is projected to occur in the same models under all three Representative Concentration Pathways (RCPs) considered (RCP2.6, RCP4.5 and RCP8.5), with the magnitude far exceeding the warming to date under the two scenarios with higher emissions (RCP4.5 and RCP8.5).

Rapid warming of Arctic marine ecosystems has led to a change in the spatial distribution of fish communities, with boreal communities expanding into regions previously dominated by Arctic fish species, which are now retracting northwards. Arctic marine ecosystems are warming twice as fast as the global average1. As a consequence of warming, many incoming species experience increasing abundances and expanding distribution ranges in the Arctic2. The Arctic is expected to have the largest species turnover with regard to invading and locally extinct species, with a modelled invasion intensity of five times the global average3. Studies in this region might therefore give valuable insights into community-wide shifts of species driven by climate warming. We found that the recent warming in the Barents Sea4 has led to a change in spatial distribution of fish communities, with boreal communities expanding northwards at a pace reflecting the local climate velocities5. Increased abundance and distribution areas of large, migratory fish predators explain the observed community-wide distributional shifts. These shifts change the ecological interactions experienced by Arctic fish species. The Arctic shelf fish community retracted northwards to deeper areas bordering the deep polar basin. Depth might limit further retraction of some of the fish species in the Arctic shelf community. We conclude that climate warming is inducing structural change over large spatial scales at high latitudes, leading to a borealization of fish communities in the Arctic.

Populations may exhibit different sensitivity to climate change depending on where they occur in their climatic range. Experimental results now show that tree species growing nearest to their warm range limit exhibit reduced net photosynthesis and growth in response to warming, whereas those near their cold range limit show improved functioning.

These are my studies of Climate Change and events that are affecting the entire solar system. For decades more and more natural disasters have been occurring and the temperature on earth is increasing. After several studies, I developed a new theory for both Global Warming and many other unpublished matters.

Research is needed by global change scientists on how global vegetation biomes respond to ongoing climate warming. To address this issue, we selected study sites with significant climate warming for diverse vegetation biomes, and used global gridded temperature and remote sensing data over the past 32 years (1982–2013). The results suggested that climate warming in areas above approximately 60° N is relaxing the heat-constraints on vegetation activity, thus promoting plant growth; whereas, in mid to low latitude areas, ongoing climate warming probably imposes negative impacts on vegetation biomes through drought and heat stress. Understanding these potential effects is important for planning adaptation strategies to mitigate the impacts of climate warming, particularly for agro-ecosystems.

Agriculture directly contributes about 10%-12% of current global anthropogenic greenhouse gas emissions, mostly from livestock. However, such percentage estimates are based on global warming potentials (GWPs), which do not measure the actual warming caused by emissions and ignore the fact that methane does not accumulate in the atmosphere in the same way as CO2 . Here, we employ a simple carbon cycle-climate model, historical estimates and future projections of livestock emissions to infer the fraction of actual warming that is attributable to direct livestock non-CO2 emissions now and in future, and to CO2 from pasture conversions, without relying on GWPs. We find that direct livestock non-CO2 emissions caused about 19% of the total modelled warming of 0.81°C from all anthropogenic sources in 2010. CO2 from pasture conversions contributed at least another 0.03°C, bringing the warming directly attributable to livestock to 23% of the total warming in 2010. The significance of direct livestock emissions to future warming depends strongly on global actions to reduce emissions from other sectors. Direct non-CO2 livestock emissions would contribute only about 5% of the warming in 2100 if emissions from other sectors increase unabated, but could constitute as much as 18% (0.27°C) of the warming in 2100 if global CO2 emissions from other sectors are reduced to near or below zero by 2100, consistent with the goal of limiting warming to well below 2°C. These estimates constitute a lower bound since indirect emissions linked to livestock feed production and supply chains were not included. Our estimates demonstrate that expanding the mitigation potential and realizing substantial reductions of direct livestock non-CO2 emissions through demand and supply side measures can make an important contribution to achieve the stringent mitigation goals set out in the Paris Agreement, including by increasing the carbon budget consistent with the 1.5°C goal.

Global warming is the rise in the average temperature of Earth’s atmosphere and oceans since the late 19th century and its projected continuation. Since the early 20th century, Earth’s mean surface temperature has increased by about 0.8 °C (1.4 °F), Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases produced by human activities such as the burning of fossil fuels and deformation. Climate model projections were summarized in 21st Century Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC). They indicated that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9°C (2 to 5.2 °F) for their lowest emission scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations. The Earth’s average surface temperature rose by .74 ± 0.18 °C over the period 1906–2005.Temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade). Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geo engineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic climate change. Reports published by the United Nations Environment Programme (UNEP) and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC’s 2 °C target. Future of climate change and associated impacts will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well a probable expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost and sea ice. Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation.

The science that humans are the cause of global warming, and that the associated climate change would lead to serious changes in climate extreme events, food production, freshwater resources, biodiversity, human mortality, etc. is unequivocal. After several political negotiations, a 2 °C warming has been considered to be the benchmark for such damaging changes. However, an increasing amount of scientific research indicates that higher levels of warming are increasingly likely. What would the world be like if such higher levels of warming occurred? This study aims to provide information for better politically driven mitigation through an investigation of the changes in temperature- and precipitation-based extreme indices using CMIP5 (coupled model intercomparison project phase 5) simulations of a warming of 1, 2, and 3 °C in China. Warming simulations show more dramatic effects in China compared with the global average. In general, the results show relatively small change signals in climate extreme events in China at 1 °C, larger anomalies at 2 °C, and stronger and more extended anomalies at 3 °C. Changes in the studied temperature indices indicate that warm events would be more frequent and stronger in the future, and that cold events would be reduced and weakened. For changes in the precipitation indices, extreme precipitation generally increases faster than total wet-day precipitation, and China will experience more intensified extreme precipitation events. Furthermore, the risk of flooding is projected to increase, and the dry conditions over northern China are projected to be mitigated. In certain regions, particularly Southwest China, the risks of both drought and flood events would likely increase despite the decreased total precipitation in the future. Uncertainties mainly derived from inter-model and scenario variabilities are attached to these projections, but a high model agreement can be generally observed in the likelihood of these extreme changes.

Aim Correlative models that forecast extinction risk from climate change and invasion risks following species introductions, depend on the assumption that species’ current distributions reflect their climate tolerances (‘climatic equilibrium’). This assumption has rarely been tested with independent distribution data, and studies that have done so have focused on species that are widespread or weedy in their native range. We use independent data to test climatic equilibrium for a broadly representative group of species, and ask whether there are any general indicators that can be used to identify when equilibrium occurs.

According to the early anthropogenic hypothesis, land clearing and agriculture caused emissions of greenhouse gases to begin to alter climate as early as 7000 years ago (Ruddiman, 2003). Climate-model simulations based on the CO2 and CH4 concentrations proposed in the hypothesis suggest that humans caused a global mean warming of 0.9 to 1.5°C before the start of the industrial era. Additional pre-industrial effects on land surface reflectance (changes in albedo resulting from forest clearance) may have cooled climate enough to cancel 0.2 to 0.3°C of this warming effect, leaving a net early anthropogenic warming contribution of between 0.7°C and 1.2°C. This proposed early anthropogenic warming is comparable with, and likely larger than, the measured 0.85°C warming during the last 150 years. If the simulations based on the early anthropogenic hypothesis are correct, total anthropogenic warming has been twice or more the industrial amount registered to date.

Climate change and global warming are important phenomena and do not mean the same thing as is wrongly conceived by some individuals. However, the link between the two is strong and one, global warming is strictly an average increase in the temperature of the atmosphere near the earth’s surface and in the troposphere, while the other, climate change is more diverse and refers to any significant change in measures of climate such as temperature, precipitation, or wind lasting for a long period of time usually several years. Climate change could thus be an increase or decrease in temperature. The most important of the two terms which is under spotlight is global warming, an increase in temperature which has been blamed largely to greenhouse effect. There can no longer be any doubt that the earth’s climate is changing. It is now obvious that even the most hardened sceptics are starting to waiver in their convictions. Climate has been thrown completely out of kilter and each day brings fresh proof such as frequent and more violent cyclones in the Caribean, floods in Africa, the Philippines, the gradual sinking of Islands in the Pacific, heat waves in Europe and the melting of glaciers. There is increase in global average air and ocean temperatures, widespread melting of snow and rising global average sea level. Impacts of global warming include the emergence and re-emergence of some parasitic infections and diseases.

Temperate-zone species have responded to warming temperatures by shifting their distributions poleward and upslope. Thermal tolerance data suggests that tropical species may respond to warming temperatures even more strongly than temperate-zone species, but this prediction has yet to be tested. We addressed this data gap by conducting resurveys to measure distributional responses to temperature increases in the elevational limits of the avifaunas of two geographically and faunally independent New Guinean mountains, Mt. Karimui and Karkar Island, 47 and 44 y after they were originally surveyed. Although species richness is roughly five times greater on mainland Mt. Karimui than oceanic Karkar Island, distributional shifts at both sites were similar: upslope shifts averaged 113 m (Mt. Karimui) and 152 m (Karkar Island) for upper limits and 95 m (Mt. Karimui) and 123 m (Karkar Island) for lower limits. We incorporated these results into a metaanalysis to compare distributional responses of tropical species with those of temperate-zone species, finding that average upslope shifts in tropical montane species match local temperature increases significantly more closely than in temperate-zone montane species. That tropical species appear to be strong responders has global conservation implications and provides empirical support to hitherto untested models that predict widespread extinctions in upper-elevation tropical endemics with small ranges.

Anthropogenic climate change is a key threat to global biodiversity. To inform strategic actions aimed at conserving biodiversity as climate changes, conservation planners need early warning of the risks faced by different species. The IUCN Red List criteria for threatened species are widely acknowledged as useful risk assessment tools for informing conservation under constraints imposed by limited data. However, doubts have been expressed about the ability of the criteria to detect risks imposed by potentially slow-acting threats such as climate change, particularly because criteria addressing rates of population decline are assessed over time scales as short as 10 years. We used spatially explicit stochastic population models and dynamic species distribution models projected to future climates to determine how long before extinction a species would become eligible for listing as threatened based on the IUCN Red List criteria. We focused on a short-lived frog species (Assa darlingtoni) chosen specifically to represent potential weaknesses in the criteria to allow detailed consideration of the analytical issues and to develop an approach for wider application. The criteria were more sensitive to climate change than previously anticipated; lead times between initial listing in a threatened category and predicted extinction varied from 40 to 80 years, depending on data availability. We attributed this sensitivity primarily to the ensemble properties of the criteria that assess contrasting symptoms of extinction risk. Nevertheless, we recommend the robustness of the criteria warrants further investigation across species with contrasting life histories and patterns of decline. The adequacy of these lead times for early warning depends on practicalities of environmental policy and management, bureaucratic or political inertia, and the anticipated species response times to management actions.

Predicting extinction in a changing world There is great interest in understanding how species might respond to our changing climate, but predictions have varied greatly. Urban looked at over 130 studies to identify the level of risk that climate change poses to species and the specific traits and characteristics that contribute to risk (see the Perspective by Hille Ris Lambers). If climate changes proceed as expected, one in six species could face extinction. Several regions, including South America, Australia, and New Zealand, face the greatest risk. Understanding these patterns will help us to prepare for, and hopefully prevent, climate-related loss of biodiversity. Science , this issue p. 571 ; see also p. 501

Since the beginning of the Industrial Revolu- tion during the late eighteenth to the early nineteenth centuries, there has been rapidly increasing release of greenhouse gases, notably CO2, into the atmosphere. As a consequence of this atmospheric change, the Earth's average surface temperature has increased by approxi- mately 0.6 C over the last 100 years. The rate of release of greenhouse gases continues to increase, and global surface temperature rose by approximately 0.2 C per decade in the last 30 years, a rate that is greater than at any other time during the last 1,000 years. The wide-ranging effects of these increases in greenhouse gases and temperature on the biosphere are subject to intense scientific study. Much has been learned, but much more needs to be elucidated, if we are to predict how terrestrial and aquatic ecosystems will be affected by global change. This brief review focuses on the marine environment and offers a concise summary of some of the important advances in our knowledge about the impacts of global change, including physical and chemical changes of the ocean, as well as the impact of ocean warming on marine organisms. Our analysis also points out areas where critical new information is needed if we are to predict the future of marine ecosystems in a warming world with accuracy.

The phenology of vegetation, particularly the length of the growing season (LOS; i.e., the period from greenup to senescence), is highly sensitive to climate change, which could imply potent feedbacks to the climate system, for example, by altering the ecosystem carbon (C) balance. In recent decades, the largest extensions of LOS have been reported at high northern latitudes, but further warming-induced LOS extensions may be constrained by too short photoperiod or unfulfilled chilling requirements. Here, we studied subarctic grasslands, which cover a vast area and contain large C stocks, but for which LOS changes under further warming are highly uncertain. We measured LOS extensions of Icelandic subarctic grasslands along natural geothermal soil warming gradients of different age (short term, where the measurements started after 5 years of warming and long term, i.e., warmed since 50 years) using ground-level measurements of normalized difference vegetation index. We found that LOS linearly extended with on average 2.1 days per degrees C soil warming up to the highest soil warming levels (ca. +10 degrees C) and that LOS had the potential to extend at least 1 month. This indicates that the warming impact on LOS in these subarctic grasslands will likely not saturate in the near future. A similar response to short- and long-term warming indicated a strong physiological control of the phenological response of the subarctic grasslands to warming and suggested that genetic adaptations and community changes were likely of minor importance. We conclude that the warming-driven extension of the LOSs of these subarctic grasslands did not saturate up to +10 degrees C warming, and hence that growing seasons of high-latitude grasslands are likely to continue lengthening with future warming (unless genetic adaptations or species shifts do occur). This persistence of the warming-induced extension of LOS has important implications for the C-sink potential of subarctic grasslands under climate change.

This is the peer reviewed version of the following article: Descamps S, Anker‐Nilssen T, Barrett RT, et al. Circumpolar dynamics of a marine top‐predator track ocean warming rates. Glob Change Biol. 2017;23:3770–3780. https://doi.org/10.1111/gcb.13715, which has been published in final form at https://doi.org/10.1111/gcb.13715 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Global warming is a nonlinear process, and temperature may increase in a stepwise manner. Periods of abrupt warming can trigger persistent changes in the state of ecosystems, also called regime shifts. The responses of organisms to abrupt warming and associated regime shifts can be unlike responses to periods of slow or moderate change. Understanding of nonlinearity in the biological responses to climate warming is needed to assess the consequences of ongoing climate change. Here, we demonstrate that the population dynamics of a long-lived, wide-ranging marine predator are associated with changes in the rate of ocean warming. Data from 556 colonies of black-legged kittiwakes Rissa tridactyla distributed throughout its breeding range revealed that an abrupt warming of sea-surface temperature in the 1990s coincided with steep kittiwake population decline. Periods of moderate warming in sea temperatures did not seem to affect kittiwake dynamics. The rapid warming observed in the 1990s may have driven large-scale, circumpolar marine ecosystem shifts that strongly affected kittiwakes through bottom-up effects. Our study sheds light on the nonlinear response of a circumpolar seabird to large-scale changes in oceanographic conditions and indicates that marine top predators may be more sensitive to the rate of ocean warming rather than to warming itself.

The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.

This study investigates future impacts of global warming on climate and extreme climate events in Nigeria, the most populous African country that depends on rain-fed agriculture. Past and future climate simulations from 9 GCMs were downscaled (using a statistical model) and analyzed for the study. The study considers the impacts of two emission scenarios (B1 and A2) on the future climates (2046–2065 and 2081–2100) over ecological zones in Nigeria. The model evaluation shows that the downscaling adds values to the GCMs simulation, and the results capture all the important climatic features over the country. The model projections show that both B1 and A2 scenarios change the future climate over Nigeria. They significantly increase the temperature over all the ecological zones, with greatest warming (between 1 and 4 °C) over the Sudan (short grass) Savanna in March. The warming, which increases the occurrence of extreme temperature and heat wave events over the entire country, enhances the frequency of the extreme rainfall events in the south and southeast and reduces the annual rainfall over the northeast. Since heavy rains and floods are major problems in the south and southeast, and drought is major problem in the northeast, the global warming may further aggravate these environmental problems in future. These could have negative impacts on agriculture and further threaten livelihood and food security in the rapidly growing country. Hence, there is need for further studies on adaptation and mitigation strategies to address the impacts of global warming in Nigeria.

The Antarctic Peninsula is one of three areas of the globe currently experiencing rapid regional climate change (King, 1994; Smith et al., 1996, King & Harangozo, 1998; Vaughan et al., 2003). The Second Assessment Report of the IPCC (Nicholls et al.,1995) demonstrated two areas of rapid atmospheric warming at northern high-latitudes, namely northwestern North America, and an area centred on the Siberian Plateau. A subsequent analysis by Hansen et al., (1999) revealed a third region of warming centred on the Antarctic Peninsula and Bellingshausen Sea. In each of these areas, mean annual temperatures have warmed by more than 1.5 K since 1950, compared to a global mean of 0.6 K. The Fourth Assessment Report (AR4) of the IPCC (Trenberth et al.,2007) confirmed key regions of rapid atmospheric warming over northwestern North America and the Siberian Plateau in the period 1901–2005 along with the rapid warming observed over the Antarctic Peninsula in the last 50 years.

Measurements show that the Earth’s global-average near-surface temperature has increased by about 0.8℃ since the 19th century. It is critically important to determine whether this global warming is due to natural causes, as contended by climate contrarians, or by human activities, as argued by the Intergovernmental Panel on Climate Change. This study updates our earlier calculations which showed that the observed global warming was predominantly human-caused. Two independent methods are used to analyze the temperature measurements: Singular Spectrum Analysis and Climate Model Simulation. The concurrence of the results of the two methods, each using 13 additional years of temperature measurements from 1998 through 2010, shows that it is humanity, not nature, that has increased the Earth’s global temperature since the 19th century. Humanity is also responsible for the most recent period of warming from 1976 to 2010. Internal climate variability is primarily responsible for the early 20th century warming from 1904 to 1944 and the subsequent cooling from 1944 to 1976. It is also found that the equilibrium climate sensitivity is on the low side of the range given in the IPCC Fourth Assessment Report.

A model based on Watson’s power law for the species-area relationship predicts that full global warming, projected up to the year 2050, could provoke the disappearance of roughly one-quarter of existing species. Here, an alternative approach is worked out, based on the combination of two ecology laws: Taylor and Watson’s power laws, where the former relates species variability with their mean abundance. Just how severely global warming would affect not only the number but the diversity of the surviving species is addressed by this approach, while at the same time giving indications for the post-disaster fate of the remaining species (extinction or recovery).

35 Abstract Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date.