Australia ranks 6th in the world in the amount of forest area, with about 134 Mha (FAO 2020), after Russia, Brazil, Canada…, the countries where you might think forests really are, not in the dry Australian continent.
Keep reading if interested
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Although Australia does have extensive, diverse and beautiful forests, the very large area claimed is because of the decision by the Government to report forest extent based on forests equal or taller than 2 m, while the rest of the countries report on taller than 5 m.
There are reasons for the choice of 2 m over 5 m, including perhaps that the FAO forest definition is a Northern Hemisphere view of what a forest should look like.
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In the end, definitions need to serve their purpose in the first place (structure, function, biodiversity, resources).
And regardless of the forest definition, even single trees outside of forests play an important role.
And speaking of beautiful forests in Australia, the photo in the first tweet in this thread, here repeated, is from the Atherton Tablelands in Queensland.
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We talk a lot about tipping points in the Climate System, yet we have so little hard evidence
In @BoZheng18 et al, we report a sharp tipping point of climatic drought in the boreal region, which has led to an exponential increase in fire CO2 emissions over the past 10ys
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Although many ecological thresholds have already been identified in response to climate change (see:
), few have been demonstrated at scales that matter to the global climate.
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The implication of this boreal tipping point certainly justifies further attention.
The 2021 emissions peak, on a trend initiated 10 years ago, was the single largest fire CO2 emission event of the last two decades, more than twice larger than the Australian fires in 2019
This figure is one of the many great figures of IPCC AR6 WGI
It is the first time in 30 years+ of IPCC that a fig. on carbon sinks is published in the Summary for Policy Makers, the one document with most readers, including governments, & often the only one read.
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According to Earth System Models, cumulat. C sinks will be larger with higher emissions to 2100, even including the hottest scenario
The growth in atmospheric CO2 drives the increased sinks, which offsets and surpasses the negative impacts of climate, particularly warming
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However, the total fraction of emissions removed by the land and ocean sinks is smaller in higher emission scenarios. That is, we get relatively more help from nature in low emission scenarios than in high emission scenarios.
It is unequivocal that the increases in atmospheric CO2, CH4, & N2O since pre-industrial are caused by human activities.
The 3 GHGs are responsible for 2/3 of global warming, with synthetic gases, carbon monoxide, and black carbon responsible for the rest.
Fig5.4
Current atmospheric concentrations of CO2, CH4 and N2O are higher than at any point in the last 800,000 years. For CO2, concentrations are unprecedented in the last 2 million years.
Ch5, Fig. 5.3
Equally important but less discussed is the rate at which CO2 concentrations are changing now
10x faster than any other time during the last 800,00 yrs;
4-5x faster than during the last 56 Myrs.
These high velocities leave us with no analog in the paleorecord to study impacts
Our new assessment of forest fires in Australia shows a multi-decadal increase in the burned area and a markedly increase in mega-fire years burning more than 1 million hectares.
We analyzed trends in the burned area using satellite + ground-based observations and in 9 wildfire risk factors and indices that relate to characteristics of fire weather, extreme fire behaviour, fuel loads, and ignition for forests in Australia.
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Forest burned area has increased linearly over the past three decades at a rate of 48,000 ha/yr.
Comparing 1988-2001 with 2002-2019, the mean burned area had increased by 350% before the Black Summer fires (2019) and by 500-800% when including 2019.