THREAD

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 2/4

Although many ecological thresholds have already been identified in response to climate change (see:

https://twitter.com/pepcanadell/status/1408314046034579456?s=20

), few have been demonstrated at scales that matter to the global climate.

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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. 2/10

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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IPCC infographics of the three most important GHG BUDGETS:

CO2, CH4, N2O

They include the main anthropogenic and natural sources and sinks. 2/5
Carbon Budget

Fossil fuels are the dominant anthropogenic source

Large natural fluxes sensitive to climate change

Of all CO2 emitted to the atmosphere from human activities:

46% accumulates in atmosphere
23% taken by ocean
31% stored in terrestrial ecosystems

THE CONTEXT

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

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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.

nature.com/articles/s4146…
@NatureComms 2/n

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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One of the most sobering sets of figures we produce every year for the Global Carbon Budget release is the energy consumption by source (BP data).

It shows the enormity of the clean energy challenge and the need for aggressive and uncompromising mitigation commitments. 2/n

EU27
Each country has a unique energy mix that will bring different challenges in developing its pathway to decarbonization

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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 2/n

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.

THREAD

The Australia State of the Climate 2020 is out, by @CSIRO and @BOM_au

Australia, more than ever before, ground zero on climate change and impacts.

Need to step up on mitigation and adapt to the extent is possible.

bit.ly/32Ejod4 Number of extreme hot days

I am disappointed that Science has allowed an abstract of a, otherwise good, paper to say that planting trees is "our most effective climate change solution to date". This is factually wrong and certainly a distraction. 1/2
bit.ly/2LBUbID Planting trees is certainly an important part of the climate change mitigation portfolio, but are neither cheaper nor easier to implement than other options. Most importantly, it won't fix the climate problem, albeit it should be part of the solution. 2/2