Carbon emissions must hit zero by 2100, warns urgent UN report

UN warns of new deadline for climate change action

It is extremely likely that rising sea levels, diminishing snow and ice and warmer oceans are the result of greenhouse gas emissions, according to a comprehensive new assessment released in Copenhagen on Sunday.

The report, published by the UN’s Intergovernmental Panel on Climate Change (IPCC), emphasises the paramount urgency with which human behaviour must be adapted in order to cut carbon emissions.

Failure to act will result in ‘severe, pervasive and irreversible impacts for people and ecosystems’, the report says.

Analysing present observed changes as well as future risks, the report nevertheless states that options to mitigate the impact of climate change exist ‘in every major sector’.

Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850, the IPCC finds, and emissions from fossil fuels are continuing to rise to record levels.

This indicates that governments and investors are still failing to heed scientific warnings. The report comes just over a year before the scheduled UN conference in Paris, whose goal is to limit the global temperature increase to 2 degrees Celsius above pre-industrial levels.

Current options for environmental damage control include bioenergy, carbon capture control, nuclear, and wind and solar power, the panel states. But the longer the delay in financing these technologies, the more expensive and difficult it will become to utilise them in the future.

One of the key issues covered in the report is the irreversibility of changes already observed. Even if  emission of greenhouse gases were stopped now, the effects of past emissions would continue for centuries. Furthermore, ‘stabilisation of global average surface temperature does not imply stabilisation for all aspects of the climate’, because ice sheets,ocean temperatures and other affected ecosystems all work according to different time scales.

Without substantial mitigation efforts, and potentially even with these, 2100 looks likely to see ‘substantial species extinction, global and regional food insecurity, consequential constraints on common human activities’.

Throughout the 21st century climate change is also expected to have an adverse effect on human health, particularly for those in developing countries. The report emphasises the inequity of the situation, stating that many of those most vulnerable to the effects of carbon emissions have contributed very little to the problem themselves.

The UN’s assessment states for the first time the ultimate aim to cut greenhouse gas emissions to zero by 2100 at the latest. The panel recommends an integrated approach that depends on cooperation on all scales,  including ‘effective institutions and governance, innovation and investments in environmentally sound technologies and infrastructure, sustainable livelihoods, and behavioural and lifestyle choices’.

Mitigation scenarios outlined in the report offer some encouragement in an otherwise bleak state of affairs. Realisation of a scenario where carbon emissions were reduced to M 450 or 500 ppm CO2 equivalent by 2100 would mean reduced costs for achieving air quality and energy security objectives. There would also be significant co-benefits for human health, ecosystem impacts, and sufficiency of resources and resilience of the energy system, potentially cutting costs overall.

An important step is to reduce revenues from coal and oil trade. The report estimates that investment in low-carbon electricity and energy efficiency would have to rise by several hundred billion dollars per year before 2030 to curb the damage. Responsibility for change is ubiquitous, with the panel assessing that both public and private sectors should play a role in financing mitigation and adaptation.

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