land degradation impacting food security
In a report released on 8 August 2019, the Intergovernmental Panel on Climate Change (IPCC) warned that temperatures over the world's land areas are warming at about twice the global rate, expanding deserts in Australia, Africa and Asia, and impacting food security and terrestrial ecosystems and land degradation to a significant degree.
The report 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.
- Compared with current conditions, land areas have warmed by about 1.8 degrees, and global mean temperatures by 1.1 degrees.
The report, compiled by 107 authors from 52 nation, has been described as a "warning flag" about how hard we need to go to cut greenhouse gas emissions. It went on to note that 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. Australia, sub-Saharan Africa and parts of east and central Asia were mentioned as regions where rising evapo-transpiration (caused by hotter temperatures and reduced rainfall) were causing deserts to expand.
Temperatures are rising over land much faster than the global average with climate change and the thermal inertia of the oceans meant land warmed faster than the seas. Climate change would "ramp up" existing degradation through erosion caused by more intense rainfall events, 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. On the other hand, 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.
This is why the 2-degree ceiling agreed in Paris at the climate summit in 2015 is far from optimum: because two degrees "in the global" translates out to very sizeable amounts of warming in heatwave conditions over land, for example, in Moree in northern NSW where last January's average temperatures "slaughtered" previous records, beating the norm by close to 4 degrees.
Australia has warmed about a degree in the past century, and the Bureau of Meteorology says day-time temperatures were both the hottest on record in the year to June and for the first seven months of this year. Average soil moisture for the 12 months to June 30 2019 were also the lowest on record at just 8.5 per cent for the top metre, surpassing the record low of 8.7 per cent 1914-15 and compared with an average of 12 per cent, the bureau said.
The IPCC report said warming, changing precipitation patterns and the greater frequency of some extreme events "has already affected food security", and as temperatures over land increase, there is an increased propensity for changes in the intensity and seasonality of wildfires fires Extreme fire weather days are increasing in number over much of Australia, and elsewhere, and the forthcoming season is again expected to be no different.
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