Warming set to reach one degree for the first time

Monday 09th Nov 2015 by theWeather Club

Met Office data for January to September 2015 has indicated that Global mean temperatures at Earth’s surface are set to rise to more than one degree above pre-industrial levels for the first time.

The HadCRUT dataset, jointly run by the Met Office and the Climate Research Unit at the University of East Anglia, shows 2015 global mean temperature is 1.02°C (±0.11°C) above pre-industrial levels (1850-1900*).

Scientists say that the 1 degree mark will be broken in 2015 due to a combination of carbon emissions and the impact of the El Nino weather phenomenon.  

Stephen Belcher, Director of the Met Office Hadley Centre, said: "We have seen a strong El Nino develop in the Tropical Pacific this year and that will have had some impact on this year's global temperature. We've had similar natural events in the past, yet this is the first time we're set to reach the 1°C marker and it's clear that it is human influence driving our modern climate into uncharted territory."

2014 was the warmest year since records began, and it's likely that 2015 will exceed this - scientists also expect 2016 to show a similar trend.

Peter Stott, Head of Climate Monitoring and Attribution, said: "This year marks an important first but that doesn't necessarily mean every year from now on will be a degree or more above pre-industrial levels, as natural variability will still play a role in determining the temperature in any given year. As the world continues to warm in the coming decades, however, we will see more and more years passing the 1 degree marker - eventually it will become the norm."

If this figure is indeed realised, the world would then be half way towards 2°C, the gateway to dangerous warming**.  Research indicates that it is still possible to limit warming to this 2°C threshold, however the later the CO2 emissions peak, the faster the subsequent emissions cuts would need to occur in order to limit the rise. This new data is therefore expected to add pressure on political negotiations in Paris later this month aimed at securing a new global climate treaty.

*While late 19th century temperatures are commonly taken to be indicative of pre-industrial, there is no fixed period that is used as standard and a variety of other periods have been used for observational and palaeo datasets. There are limitations in available data in the early instrumental record, making the average temperature in the reference period less certain. There is not a reliable indicator of global temperatures back to 1750, which is the era widely assumed to represent pre-industrial conditions. Therefore 1850-1900 is chosen here as the most reliable reference period, which also corresponds to the period chosen by IPCC to represent a suitable earlier reference period.  

**The idea of a dangerous warming threshold was first mentioned by Yale economist William Nordhaus in the 1970s. In 1990, the Stockholm Environmental Institute came forward with a more definitive statement that 2°C should be taken as the level at which dangerous warming would occur. The first political body to declare that 2°C was the goal, was the 1996 European Council of environment ministers, which included a young Angela Merkel as the German representative.

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