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World on track for catastrophic warming – forecasters

The level of greenhouse gas emissions being produced around the world means that, as things stand, temperatures are likely to rise by around 4.5 degrees by 2100, unless significant reductions are agreed, sophisticated climate simulations show.
Researchers have estimated the five-year mean forecast from November 2014 and found that the global average temperature is expected to remain high, with specific regions varying between one-and-a-half degrees cooler to one-and-a-half degrees warmer. This work was supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101).
The level of greenhouse gas emissions being produced around the world means that, as things stand, temperatures are likely to rise by around 4.5 degrees by 2100, unless significant reductions are agreed, sophisticated climate simulations show.

‘Emissions at the moment track closely the worst scenarios used for estimating future climate change,’ said Professor Colin Jones from the University of Leeds, who is based at the Met Office, UK. ‘If we look at actual emissions over the past 15 years and just plot them as a line, they generally follow the worst-case scenario… in our modelling studies.’

It means that, unless emissions are seriously curbed, we’re in line for a global mean temperature increase of around 4.5 degrees Celsius by 2100, compared with average temperatures from the pre-industrial era.

‘Those estimates, plus or minus 10 % to 20 %, I would be very confident in,’ said Prof. Jones, coordinator of the CRESCENDO project, which is working to better understand how climate change will affect the way that the oceans and vegetation absorb CO2 from the atmosphere by the end of the century.

Even in the next five years, temperatures are likely to be between 0.18 and 0.46 degrees Celsius higher than the average from 1981 to 2010, and it’s going to make a noticeable difference around areas such as the Mediterranean.

‘In 10 years’ time, it will be even worse than it is now, so that’s the kind of problem we are addressing, (that’s) the urgency of climate change,’ said Professor Francisco Doblas-Reyes from the Catalan Institute of Climate Sciences, Spain.

Prof. Doblas-Reyes is the cordinator of the SPECS project, which has generated these revolutionary new close-range climate forecasts using high-powered computer simulations.

The Issue

As world leaders meet in Paris to try to agree on ambitions emissions reduction targets, the one thing they need to know is what will happen if they fail.

That’s where climate modelling comes in. Around the world, climate scientists are using supercomputers to try to predict how the climate will change in the decades and centuries ahead as a result of decisions made today.

To give them the best possible chance of being accurate, they compare the results of the different simulations as part of an international project called the Coupled Model Intercomparison Project, or CMIP6, and then use the outcomes that appear most often from different models to make the final forecasts.

Climate researchers are able to make projections like this with some confidence, as they run their simulations many times from points in the past and evaluate them against the observed conditions to make sure that everything they now know about the climate is taken into account.

That has shown that, while the models still have a number of deficiencies, they are increasingly able to simulate many observed features of the global climate system and its response to rising CO2 levels.

World leaders

It’s critically important that climate model projections are as realistic as possible as their results will be used by world leaders during the COP21 climate negotiations in Paris at the end of November, where countries will try to agree ambitious emission reduction targets.

CRESCENDO and SPECS, both funded by the EU, are coordinating their work with other projects around the world in order to improve the accuracy of climate simulations so they can inform the UN’s Intergovernmental Panel on Climate Change as it makes a new assessment of the threat of global warming.

One such improvement would be to increase the resolution of climate models, and that’s work being done by the EU-funded PRIMAVERA project, jointly led by the UK’s Met Office and the University of Reading.

At the turn of the century, climate models were worked out on grid squares representing the earth’s surface of 200 kilometres on each side, whereas the goal of PRIMAVERA is to cut that to squares of 25 kilometres on each side.

‘We really want to get to the kind of resolution that a weather forecast uses,’ said project coordinator Dr Malcolm Roberts.

It’s important because current climate models lump very different geographical features into a single forecast.

‘In a typical climate model, the Alps would influence Paris weather,’ said Dr Roberts. ‘In the real world, the Alps influence weather around that part of France, but they don’t really influence what happens in Paris.’

The data is not just for policymakers, it is also being used to inform businesses and the public about the impact of climate change.

The EU-funded PRIMAVERA project is planning to talk to people such as city planners and energy companies in order to find out exactly what kind of information on climate change they will need.

Wind farm

‘It’s very much a two-way interaction,’ said Dr Roberts. ‘Say for a wind farm … what information does a wind farm need in order that they can make a plan for 20 years into the future?’

‘Those estimates, plus or minus 10 % to 20 %, I would be very confident in.’

Prof. Colin Jones, University of Leeds, UK

The new models under development will be able to feed into the EU’s Copernicus Climate Change Service and other international networks to give businesses and governments an idea of what impact climate change will have on them.

‘The project is linked to lots of other international initiatives which is very good for research and very good for disseminating and making sure the results are published widely into the research community and beyond it,’ said PRIMAVERA project manager Paul van der Linden.

These projections will also be used to give the general public a better idea of how climate change will affect them over the next few years.

‘The main weather services in Europe are going to make this information publicly available for their own countries and translated into indices that are relevant to them, like the number of hours of sunshine,’ added Prof. Doblas-Reyes, who is also a partner in PRIMAVERA.

‘But this is something that will still take a couple of years before it happens.’

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