From The Sydney Morning Herald (Peter Hannam):
Temperatures over the world’s land areas are warming at about twice the global rate, expanding deserts in Australia, Africa and Asia, and hitting food security hard, a new UN report finds.
The Intergovernmental Panel on Climate Change (IPCC) found that surface air temperatures between 2006 and 2015 were 1.53 degrees warmer than the pre-industrial average of 1850-1900. By contrast, the combined warming of land and oceans was 0.87 degrees, the IPCC’s special report on land said.
Compared with current conditions, though, land areas have warmed by about 1.8 degrees, and global mean temperatures by 1.1 degrees, said Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research.
“Climate change, including increases in frequency and intensity of extremes, has adversely impacted food security and terrestrial ecosystems, as well as contributed to desertification and land degradation in many regions,” the report’s Summary for Policymakers said.
The report, compiled by 107 authors from 52 nations and released in Geneva on Thursday, noted humans typically relied on land for their homes and the great bulk of their food, fibre and feed for animals.
Mark Howden, director of the Climate Change Institute at the Australian National University and an IPCC vice-chair, said the report was “a warning flag” about the threats and “how hard we need to go” to cut greenhouse gas emissions.
Land’s effect on climate
About a quarter of the earth’s ice-free land was already subject to human-caused degradation, with soil losses as much as 100 times higher than soil formation, the report said.
Australia, sub-Saharan Africa and parts of east and central Asia were singled out as regions where rising evapotranspiration (caused by hotter temperatures and reduced rainfall) were causing deserts to expand.
Climate change would “ramp up” existing degradation, such as through erosion caused by more intense rainfall events, Professor Howden said.
But land would also affect the climate because land-clearing, methane from livestock, fertiliser, and other emissions related to farming and forestry are major sources of greenhouse gases.
“Just under a third of our emissions come from our food systems, globally,” he said.
On the flip side, reducing land clearing and increasing soil carbon sequestration would help reduce the damaging trends, as would consumers switching to more plant-based diets rather than meat-based ones, the report said.
Here’s the link to the IPCC report Climate Change and Land: Summary for Policy Makers:
This Special Report on Climate Change and Land responds to the Panel decision in 2016 to prepare three Special Reports during the Sixth Assessment cycle, taking account of proposals from governments and observer organizations. This report addresses greenhouse gas (GHG) fluxes in land-based ecosystems , land use and sustainable land management in relation to climate change adaptation and mitigation, desertification, land degradation6 and food security. This report follows the publication of other recent reports, including the IPCC Special Report on Global Warming of 1.5°C (SR15), the thematic assessment of the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) on Land Degradation and Restoration, the IPBES Global Assessment Report on Biodiversity and Ecosystem Services, and the Global Land Outlook of the UN Convention to Combat Desertification (UNCCD). This report provides an updated assessment of the current state of knowledge8 while striving for coherence and complementarity with other recent reports.