A landmark United Nations report paints a dire picture of the catastrophic consequences the world will face if immediate action is not taken to limit the global warming to 1.5°C, warning that at 2°C, the world could see 10 cm more global sea level rise, loss of all coral-reefs and worsening food shortages.
The Australian prime minister Scott Morrison says the Coalition will look carefully at the Intergovernmental Panel on Climate Change report which was released on Monday.
"Every extra bit of warming matters, especially since warming of 1.5°C or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some eco-systems", CNN quoted Hans-Otto Pörtner, Co-Chair of IPCC Working Group II, as saying. By 2100, global sea level rise would be 10 cm lower with global warming of 1.5°C compared with 2°C. Even at 1.5°C, the report says there is "high confidence" that coral reefs will further decline by 70 to 90 percent.
"E$3 ven with erroneous attribution of extreme weather/climate events and projections using climate models that are running too hot and not fit for goal of projecting 21st century climate change, the IPCC still has not made a strong case for this massive investment to prevent 1.5C warming", she said on her Climate Etc. blog.
"The policy implications of the report are obvious: We need to implement a suite of policies to sharply limit carbon emissions and build climate resilience, and we must do all this is in a way that prioritizes equitable outcomes particularly for the world's poor and marginalized communities", Cleetus added.
"While the pace of change that would be required to limit warming to [2.7º F] can be found in the past, there is no historical precedent for the scale of the necessary transitions, in particular in a socially and economically sustainable way", the report stated.
Fifteen years later, the UNFCCC's Copenhagen Accord introduced a 2℃ target, and its 2015 Paris Agreement was even more specific: it "aims to strengthen the global response to the threat of climate change ... by holding the increase in ... temperature to well below 2℃ above pre-industrial levels and pursuing efforts to limit the ... increase to 1.5℃". And carbon dioxide emissions must reach net zero around 2075 - meaning the amount of carbon dioxide entering the atmosphere equals the amount being removed.
"With more than 6,000 scientific references cited and the dedicated contribution of thousands of expert and government reviewers worldwide, this important report testifies to the breadth and policyrelevance of the IPCC", said Hoesung Lee, Chair of the IPCC. And that would have the side benefit of avoiding more than 100 million premature deaths through this century, the report said.
Overall, the authors say that current greenhouse gas emissions must be reduced by 45 percent from 2010 levels by 2030. A 2-degree-Celsius rise in temperatures would spell widespread disaster.
The US, along with 180 other countries, accepted the report's summary line by line.
In addition, the number of global marine heatwave days in a year rises significantly too - for 1.5C, it goes up 16 times, and for 2C it is 23 times.
Climate Analytics is a global research organisation whose scientists have extensively contributed to the literature on which the IPCC has based its SR1.5 assessment.
Limiting global temperature rises to 1.5C above pre-industrial levels would put an end to burning fossil fuels to generate power.
Besides special reports, the IPCC has issued five major Assessment Reports that serve as the scientific foundation for United Nations climate talk.
It warns that overshooting 1.5 degrees C will be disastrous.
Currently, a few experimental methods exist that can snatch carbon dioxide directly out of the air, but at up to $1,000 per ton of carbon dioxide, the price tag of such carbon capture is staggering-and billions of tons await extraction.
"There are material differences between 1.5 C and 2 C", says Cleetus.
Among them would be a 40 to 50 percent reduction in emissions by 2030-a mere 12 years from now-and a completely carbon-neutral world by 2050.
"This is not a risk we can afford to take", he said.