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Assessing global mean temperature rise using the average warming over the previous one or two decades will delay formal recognition of when Earth breaches the Paris agreement's 1.5 °C guard rail. Here is what's needed to avoid the wait. [ABSTRACT FROM AUTHOR]

ARISING FROM C. Mora et al. Nature 502, 183-187 (2013) The question of when the signal of climate change will emerge from the background noise of climate variability--the 'time of [...]

Now that specific floods, heatwaves and more can be attributed to our actions, decision makers can act. Now that specific floods, heatwaves and more can be attributed to our actions, decision makers can act., Author(s): Richard A. Betts Author Affiliations: Heed blame for extreme weather In 2019, daily maximum temperatures met or broke historical records in more than 24 cities in southwest China. In [...]

The Amazon rainforest plays a crucial role in the climate system, helping to drive atmospheric circulations in the tropics by absorbing energy and recycling about half of the rainfall that [...]

Author(s): Richard A. Betts (corresponding author) [1]; Olivier Boucher [1]; Matthew Collins [1]; Peter M. Cox [1, 2]; Peter D. Falloon [1]; Nicola Gedney [3]; Deborah L. Hemming [1]; Chris [...]

Carbon uptake by forestation is one method proposed (1) to reduce net carbon dioxide emissions to the atmosphere and so limit the radiative forcing of climate change (2). But the overall impact of forestation on climate will also depend on other effects associated with the creation of new forests. In particular, the albedo of a forested landscape is generally lower than that of cultivated land, especially when snow is lying (3,9), and decreasing albedo exerts a positive radiative forcing on climate. Here I simulate the radiative forcings associated with changes in surface albedo as a result of forestation in temperate and boreal forest areas, and translate these forcings into equivalent changes in local carbon stock for comparison with estimated carbon sequestration potentials (10,12). I suggest that in many boreal forest areas, the positive forcing induced by decreases in albedo can offset the negative forcing that is expected from carbon sequestration. Some high-latitude forestation activities may therefore increase climate change, rather than mitigating it as intended., Perturbations to the balance between radiation absorbed and emitted by the Earth ('radiative forcing') can result from changes in atmospheric chemistry and planetary albedo. A positive 'greenhouse' forcing results from [...]

The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate (1). About half of the current emissions are being absorbed by the ocean and by land ecosystems (2), but this absorption is sensitive to climate (3,4) as well as to atmospheric carbon dioxide concentrations (5), creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and C[O.sub.2] concentrations from simple carbon-cycle models that do not include climate change (6). Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt [Cyr.sup.1] is balanced by the terrestrial carbon source, and atmospheric C[O.sub.2] concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon [models.sup.2], resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback., The general circulation model (GCM) that we used is based on the third Hadley Centre coupled ocean-atmosphere model, HadCM3 (7), which we have coupled to an ocean carbon-cycle model (HadOCC) [...]

The impact on a doubled-carbon dioxide climate of structural vegetation and physiological feedbacks is calculated using an equilibrium vegetation model coupled to a general circulation model. Physiological vegetation-climate feedbacks are partly offset by vegetation structure changes in the long term, although important regional-scale effects are yielded from vegetation feedbacks. Climatic change induced by a CO2-enriched atmosphere could change vegetation cover density to ultimately produce a further climate feedback.