World must stop emitting greenhouse gases by 2100, report says

Brussels - If the world wants to keep the effects of global warming to a minimum, it needs to ensure that by the year 2100, there are almost no emissions of greenhouse gases like CO2 i, according to a major new report.

In the past seven years, scientists have become more convinced that human behaviour is the cause of the world's rising average temperature.

It is “extremely likely” that human activity is “the dominant cause of the observed warming since the mid-20th century”, the Intergovernmental Panel on Climate Change (IPCC) writes in a report, which summarises what scientists know about climate change and what can be done about it.

The summary is written for policy-makers and is meant for the desks of environment ministries all over the world.

The document will also be a topic of discussion next month in Lima, when the UN will hold its annual climate conference.

The Lima summit is something of a rehearsal for 'Paris 2015', when government leaders will try to agree on how to mitigate climate change.

“We have the means to limit climate change”, Rajendra Pachauri, the IPCC's chairperson, said in a press release.

The summary for policy-makers describes how certain scientists are of climate change, its causes and what humans can do about limiting the effects.

“It is virtually certain that there will be more frequent hot and fewer cold temperature extremes” on most land areas and “very likely that heat waves will occur with a higher frequency and longer duration”.

'Virtually certain' means there is a maximum of 1 percent probability that the statement will not be true. 'Very likely' refers to a probability of 90 to 100 percent.

It is also “virtually certain that global mean sea-level rise will continue for many centuries beyond 2100”.

But the effects of climate change can be limited if the global temperature does not rise more than 2 degrees celsius.

In the scenario of a 4 degree celsius rise, for example, the IPCC expects with high confidence “substantial species extinction, global and regional food insecurity, consequential constraints on common human activities, and limited potential for adaptation in some cases”.

A scenario in which global warming does not exceed 2 degrees celsius, “would require substantial emissions reductions over the next few decades and near zero emissions of CO2 and other long-lived GHGs [greenhouse gases] by the end of the century”.

Report

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  IPCC Synthesis Report, summary for policymakers