Ten Environmental Reports

March 2024

1.  The devastating AMOC tipping point

Rene M. Van Westen, et al., “Physics-based early warning signal shows that AMOC is on tipping course,” Science Advances (9 Feb 2024).  bit.ly/3OzjXwz

Abstract
One of the most prominent climate tipping elements is the Atlantic meridional overturning circulation (AMOC), which can potentially collapse because of the input of fresh water in the North Atlantic. Although AMOC collapses have been induced in complex global climate models by strong freshwater forcing, the processes of an AMOC tipping event have so far not been investigated. Here, we show results of the first tipping event in the Community Earth System Model, including the large climate impacts of the collapse. Using these results, we develop a physics-based and observable early warning signal of AMOC tipping: the minimum of the AMOC-induced freshwater transport at the southern boundary of the Atlantic. Reanalysis products indicate that the present-day AMOC is on route to tipping. The early warning signal is a useful alternative to classical statistical ones, which, when applied to our simulated tipping event, turn out to be sensitive to the analyzed time interval before tipping.

See also, Jonathan Watts, “Atlantic Ocean circulation nearing ‘devastating’ tipping point, study finds,” The Guardian (9 Feb 2024). bit.ly/42yODE6

“The circulation of the Atlantic Ocean is heading towards a tipping point that is “bad news for the climate system and humanity”, a study has found.

The scientists behind the research said they were shocked at the forecast speed of collapse once the point is reached, although they said it was not yet possible to predict how soon that would happen…

They found Amoc is already on track towards an abrupt shift, which has not happened for more than 10,000 years and would have dire implications for large parts of the world…

The new paper…has broken new ground by looking for warning signs in the salinity levels at the southern extent of the Atlantic Ocean between Cape Town and Buenos Aires. Simulating changes over a period of 2,000 years on computer models of the global climate, it found a slow decline can lead to a sudden collapse over less than 100 years, with calamitous consequences.”

2.  The Amazon forest system tipping point

Bernardo M. Flores, et al., Critical transitions in the Amazon forest system, Nature (14 Feb 2024). go.nature.com/4bzoSrj

See also, Jonathan Watts, ““Amazon rainforest could reach ‘tipping point’ by 2050, scientists warn,” The Guardian (14 Feb 2024).  bit.ly/3SI4JGS via @guardian
“Up to half of the Amazon rainforest could hit a tipping point by 2050 as a result of water stress, land clearance and climate disruption, a study has shown…

For 65 million years, Amazonian forests have withstood climatic variability, but the region is now exposed to unprecedented stress from drought, heat, fire and land clearance, which are penetrating even the deep central areas of the biome. This is altering the functioning of the forest, which in many areas is producing less rain than before, and turning a carbon sink into a carbon emitter.

Concerns about an Amazon tipping point have been discussed for the past two decades, with previous models suggesting this could come when 20% to 25% of the forest is cleared. The new study … went further in its complexity, analysing evidence for five drivers of water stress and identifying critical thresholds that, if crossed, could trigger local, regional or even biome-wide forest collapse.

It estimated that by 2050, 10% to 47% of Amazonian forests would be exposed to compounding disturbances that might trigger unexpected ecosystem-wide transitions and have an adverse knock-on effect for regional climate change.”

3.  Need for new category of hurricanes

Michael F. Wehner and James P. Kossin, “The growing inadequacy of an open-ended Saffir–Simpson hurricane wind scale in a warming world,” PNAS (5 Feb 2024).  bit.ly/49mh1vo

See also, Oliver Milman, “Hurricanes becoming so strong that new category needed, study says,” The Guardian (5 Feb 2024). bit.ly/3OxNTcE
“Hurricanes are becoming so strong due to the climate crisis that the classification of them should be expanded to include a “category 6” storm, furthering the scale from the standard 1 to 5, according to a new study.

Over the past decade, five storms would have been classed at this new category 6 strength, researchers said, which would include all hurricanes with sustained winds of 192mph or more. Such mega-hurricanes are becoming more likely due to global heating, studies have found, due to the warming of the oceans and atmosphere.”

4.  Plant life thriving across Greenland ice sheet

Michael Grimes, et al., “Land cover changes across Greenland dominated by a doubling of vegetation in three decades,” Nature (13 Feb 2024). go.nature.com/3uG7795

See also, Rachel Keenan, “Climate experts sound alarm over thriving plant life at Greenland ice sheet,” The Guardian (13 Feb 2024). bit.ly/3OIebZI via @guardian
“Significant areas of Greenland’s melted ice sheet are now producing vegetation, risking increased greenhouse gas emissions, rising sea levels and instability of the landscape.

A study has documented the change since the 1980s and shows that large areas of ice have been replaced with barren rock, wetlands and shrub growth, creating a change in environment.

Analysis of satellite records has shown that over the past three decades an estimated 11,000 sq miles of Greenland’s ice sheet and glaciers have melted, an area equivalent to the size of Albania and amounting to 1.6% of its total ice cover.

As ice has retreated, the amount of land with vegetation growing on it has increased by 33,774 sq miles, more than twice the area covered when the study began.

The findings show a near-quadrupling of wetlands across Greenland, which are a source of methane emissions.”

5.  Polar bears managing ice-free periods

Anthony M. Pagano, et al., “Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period,” The Guardian (13 Feb 2024). bit.ly/49AA5pL
Abstract

“Declining Arctic sea ice is increasing polar bear land use. Polar bears on land are thought to minimize activity to conserve energy. Here, we measure the daily energy expenditure (DEE), diet, behavior, movement, and body composition changes of 20 different polar bears on land over 19–23 days from August to September (2019–2022) in Manitoba, Canada. Polar bears on land exhibited a 5.2-fold range in DEE and 19-fold range in activity, from hibernation-like DEEs to levels approaching active bears on the sea ice, including three individuals that made energetically demanding swims totaling 54–175 km. Bears consumed berries, vegetation, birds, bones, antlers, seal, and beluga. Beyond compensating for elevated DEE, there was little benefit from terrestrial foraging toward prolonging the predicted time to starvation, as 19 of 20 bears lost mass (0.4–1.7 kg•day−1). Although polar bears on land exhibit remarkable behavioral plasticity, our findings reinforce the risk of starvation, particularly in subadults, with forecasted increases in the onshore period.”

See also, Agence France-Presse, ”Polar bears risk starvation as they face longer ice-free periods in the Arctic,” The Guardian (13 Feb 2024). bit.ly/4bF3r8a via @guardian

6.  First-ever State of the World’s Migratory Species report

UNEP-WCMC, 2024. State of the World’s Migratory Species. UNEP-WCMC, Cambridge, United Kingdom. bit.ly/3OLj4RU

The first-ever State of the World’s Migratory Species report was launched today by the Convention on the Conservation of Migratory Species of Wild Animals (CMS), a UN biodiversity treaty, at the opening of a major UN wildlife conservation conference (CMS COP14). The landmark report reveals:

While some migratory species listed under CMS are improving, nearly half (44 per cent) are showing population declines.
More than one-in-five (22 per cent) of CMS-listed species are threatened with extinction.Nearly all (97 per cent) of CMS-listed fish are threatened with extinction.
The extinction risk is growing for migratory species globally, including those not listed under CMS.
Half (51 per cent) of Key Biodiversity Areas identified as important for CMS-listed migratory animals do not have protected status, and 58 per cent of the monitored sites recognized as being important for CMS-listed species are experiencing unsustainable levels of human-caused pressure.
The two greatest threats to both CMS-listed and all migratory species are overexploitation and habitat loss due to human activity. Three out of four CMS-listed species are impacted by habitat loss, degradation and fragmentation, and seven out of ten CMS-listed species are impacted by overexploitation (including intentional taking as well as incidental capture).
Climate change, pollution and invasive species are also having profound impacts on migratory species.
Globally, 399 migratory species that are threatened or near threatened with extinction are not currently listed under CMS.

Until now, no such comprehensive assessment on migratory species has been carried out. The report provides a global overview of the conservation status and population trends of migratory animals, combined with the latest information on their main threats and successful actions to save them.

7. Reforestation’s potential as a local climate adaptation strategy in temperate regions

Mallory L. Barnes, “A Century of Reforestation Reduced Anthropogenic Warming in the Eastern United States,” Earth’s Future (13 Feb 2024).  bit.ly/48m0uXl
Abstract
Restoring and preserving the world’s forests are promising natural pathways to mitigate some aspects of climate change. In addition to regulating atmospheric carbon dioxide concentrations, forests modify surface and near-surface air temperatures through biophysical processes. In the eastern United States (EUS), widespread reforestation during the 20th century coincided with an anomalous lack of warming, raising questions about reforestation’s contribution to local cooling and climate mitigation. Using new cross-scale approaches and multiple independent sources of data, we uncovered links between reforestation and the response of both surface and air temperature in the EUS. Ground- and satellite-based observations showed that EUS forests cool the land surface by 1–2°C annually compared to nearby grasslands and croplands, with the strongest cooling effect during midday in the growing season, when cooling is 2–5°C. Young forests (20–40 years) have the strongest cooling effect on surface temperature. Surface cooling extends to the near-surface air, with forests reducing midday air temperature by up to 1°C compared to nearby non-forests. Analyses of historical land cover and air temperature trends showed that the cooling benefits of reforestation extend across the landscape. Locations surrounded by reforestation were up to 1°C cooler than neighboring locations that did not undergo land cover change, and areas dominated by regrowing forests were associated with cooling temperature trends in much of the EUS. Our work indicates reforestation contributed to the historically slow pace of warming in the EUS, underscoring reforestation’s potential as a local climate adaptation strategy in temperate regions.

See also, Oliver Milman, “Very cool: trees stalling effects of global heating in eastern US, study finds,” The Guardian (17 Feb 2024).  bit.ly/3UKN97L

8.  Temporary drop in renewable federal power in 2023

Dan Gearino, “Federal Data Reveals a Surprising Drop in Renewable Power in 2023, as Slow Winds and Drought Took a Toll: A big increase in utility-scale solar power was not enough to offset decreases in wind and hydropower,“ Inside Climate News ( 27 Feb 2024).  bit.ly/3OZOkg2

“U.S. utility-scale renewable electricity generation fell in 2023 due to weather patterns that reduced output from wind farms and drought that affected hydropower. Data released by the Energy Information Administration shows a decrease of 0.8 percent compared to the prior year.

This is a stunning result, considering that utility-scale renewables have been a fast-growing part of the electricity mix and are a crucial resource for the country’s transition away from fossil fuels.

But experts urged caution in interpreting the results.

“There’s no reason to overreact to a one-year blip,” said Daniel Cohan, an environmental engineering professor at Rice University. “Renewable electricity is still on pace to more than double by the end of the decade as hundreds of new solar and wind farms come online.”

See full Report at , U. S. Energy Information Administration, Electric Power Monthly, February 2024      https://bit.ly/49wAE4u

9.  Doomsday Glacier

Bob Berwyn, “New Research from Antarctica Affirms The Threat of the ‘Doomsday Glacier,’ But Funding to Keep Studying it Is Running Out: In a worst case scenario, rising global temperatures and marine heatwaves could melt enough of the Thwaites Glacier and other Antarctic ice to raise sea levels 10 feet by the early 2100s,” Inside Climate News (26 Feb 2024).  bit.ly/3P2qOz7
A report in the Proceedings of the National Academies of Sciences “affirms one of the most serious concerns about Antarctica—that an irreversible meltdown of some of the frozen continent’s ice masses has already started.”

10.  Some EU countries already hitting some sustainable energy targets for 2030

Marek Walesiak and Grazyna Dehnel, “Progress on SDG 7 achieved by EU countries in relation to the target year 2030: A multidimensional indicator analysis using dynamic relative taxonomy,” PLOS ONE (28 Feb 2024).  bit.ly/3P1zUw6

See also, Ajit Niranjan, “EU countries already hitting some of their sustainable energy targets for 2030,” The Guardian (28 Feb 2024).  https://bit.ly/48urdBa
“Several European countries hit some of their sustainable energy targets for 2030 a decade early, a study has found, but big gaps remain across the board.

All EU member states made progress in the 2010s toward reaching the UN’s seventh sustainable development goal, which calls for access to “affordable, reliable, sustainable and modern energy for all” by 2030. For some indicators, several countries had already reached the targets by 2021 …

Several countries had already achieved their targets for 2030 in at least one of the indicators by 2021, the research found.

Spain, Malta and Portugal, for instance, hit the target for the average amount of energy a person consumes in a household. Denmark, Ireland and Luxembourg hit the target for energy productivity, which compares the size of an economy with the energy it consumes.”