 |
Philosophers and economists agree on climate policy paths but for different reasons - Nature Climate Change (May 25) |
|
May 25 · The estimated value to society from climate change mitigation is highly sensitive to the long-term social discount rate. Governmental discounting guidance has almost exclusively been influenced by economists, although it is not clear that they possess any special expertise on intergenerational ethics. Here, by contrast, we report the views of philosophers, who are the most trained in ethical matters. We show that, as a group, these experts offer strong support for a real social discount rate of 2%, a value that is also predominantly backed by economists. We find multidisciplinary support for climate policy paths in line with the United Nations climate targets when views on ... Read more ...
|
|
|
|
Coastal vegetation and estuaries are collectively a greenhouse gas sink - Nature Climate Change (May 22) |
|
May 22 · Coastal ecosystems release or absorb carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), but the net effects of these ecosystems on the radiative balance remain unknown. We compiled a dataset of observations from 738 sites from studies published between 1975 and 2020 to quantify CO2, CH4 and N2O fluxes in estuaries and coastal vegetation in ten global regions. We show that the CO2-equivalent (CO2e) uptake by coastal vegetation is decreased by 23–27% due to estuarine CO2e outgassing, resulting in a global median net sink of 391 or 444?TgCO2e?yr-1 using the 20- or 100-year global warming potentials, respectively. Globally, total coastal CH4 and N2O emissions decrease the ... Read more ...
|
|
|
|
Social cost of carbon estimates have increased over time - Nature Climate Change (May 15) |
|
May 15 · Estimates of the social cost of carbon are the yardstick for climate policy targets. However, there is great uncertainty and we do not know how estimates have evolved over time. Here I present a meta-analysis of published estimates showing that the social cost of carbon has increased as knowledge about climate change accumulates. Correcting for inflation and emission year and controlling for the discount rate, kernel density decomposition reveals a non-stationary distribution. In the past 10 years, estimates of the social cost of carbon have increased from US$9 per tCO2 to US$40 per tCO2 for a high discount rate and from US$122 per tCO2 to US$525 per tCO2 for a low discount rate. ... Read more ...
|
|
|
|
|
|
Macroclimate data overestimate range shifts of plants in response to climate change - Nature Climate Change (Apr 24) |
|
Apr 24 · Current conservation policy has been shaped by the expectation that, for many species, places with suitable climate will lie outside their current range, thus leading to predictions of numerous extinctions. Here we show that the magnitude of range shifts is often overestimated as climate data used do not reflect the microclimatic conditions that many organisms experience. We model the historic (1977–1995) distributions of 244 heathland and grassland plant taxa using both macro- and microclimate data and project these distributions to present day (2003–2021). Whereas macroclimate models predicted major range shifts (median 14?km shift), microclimate models predicted localized shifts, ... Read more ...
|
|
|
|
Wildfire and degradation accelerate northern peatland carbon release - Nature Climate Change (Apr 20) |
|
Apr 20 · The northern peatland carbon sink plays a vital role in climate regulation; however, the future of the carbon sink is uncertain, in part, due to the changing interactions of peatlands and wildfire. Here, we use empirical datasets from natural, degraded and restored peatlands in non-permafrost boreal and temperate regions to model net ecosystem exchange and methane fluxes, integrating peatland degradation status, wildfire combustion and post-fire dynamics. We find that wildfire processes reduced carbon uptake in pristine peatlands by 35% and further enhanced emissions from degraded peatlands by 10%. The current small net sink is vulnerable to the interactions of peatland degraded ... Read more ...
|
|
|
|
Biogenic factors explain soil carbon in paired urban and natural ecosystems worldwide - Nature Climate Change (Mar 27) |
|
Mar 27 · Urban greenspaces support multiple nature-based services, many of which depend on the amount of soil carbon (C). Yet, the environmental drivers of soil C and its sensitivity to warming are still poorly understood globally. Here we use soil samples from 56 paired urban greenspaces and natural ecosystems worldwide and combine soil C concentration and size fractionation measures with metagenomics and warming incubations. We show that surface soils in urban and natural ecosystems sustain similar C concentrations that follow comparable negative relationships with temperature. Plant productivity’s contribution to explaining soil C was higher in natural ecosystems, while in urban ... Read more ...
|
|
|
|
New damage curves and multimodel analysis suggest lower optimal temperature - Nature Climate Change (Mar 23) |
|
Mar 23 · Economic analyses of global climate change have been criticized for their poor representation of climate change damages. Here we develop and apply aggregate damage functions in three economic Integrated Assessment Models (IAMs) with different degrees of complexity. The damage functions encompass a wide but still incomplete set of climate change impacts based on physical impact models. We show that with medium estimates for damage functions, global damages are in the range of 10% to 12% of GDP by 2100 in a baseline scenario with 3?°C temperature change, and about 2% in a well-below 2?°C scenario. These damages are much higher than previous estimates in benefit-cost studies, resulting ... Read more ...
|
|
|
|
The timing of decreasing coastal flood protection due to sea-level rise - Nature Climate Change (Mar 23) |
|
Mar 23 · Sea-level rise amplifies the frequency of extreme sea levels by raising their baseline height. Amplifications are often projected for arbitrary future years and benchmark frequencies. Consequently, such projections do not indicate when flood risk thresholds may be crossed given the current degree of local coastal protection. To better support adaptation planning and comparative vulnerability analyses, we project the timing of the frequency amplification of extreme sea levels relative to estimated local flood protection standards, using sea-level rise projections of IPCC AR6 until 2150. Our central estimates indicate that those degrees of protection will be exceeded ten times as ... Read more ...
|
|
|
|
Weakening greenhouse gas sink of pristine wetlands under warming - Nature Climate Change (Mar 20) |
|
Mar 20 · Pristine wetlands have high potential for mitigating climate change because of their large carbon stocks. However, whether and where wetlands will act as a greenhouse gas sink or source under warming is uncertain. Here we report the observations from 167 sites of the responses of carbon dioxide, methane and nitrous oxide emissions to experimental warming in northern wetlands between latitudes 30°?N and 80°?N during the period 1990–2022. We show that the 100-year global warming potential of wetlands increased by 57% in response to an average temperature increase of 1.5–2.0?°C. The difference in dominant plant functional types explains the uncertainties in emissions. Although warming ... Read more ...
|
|