What is global warming and what effect is it having on the earth? From rising sea levels to flooding
A new report suggests that to even have a 50-50 chance of staying under the temperature the world has to be carbon neutral by 2050
Glaciers are now sliding into the sea because of the warming of the Southern Ocean as ice vanishes five times faster than it did in the 1990s.
But what exactly is global warming, and what impact is it having on our planet? Here's what we know about the man-made crisis and what's being done to fight it.
What is global warming and what caused it?
Global warming describes a set of changes to the climate that is causing the Earth to heat up.
This rising of the Earth's temperature is often talked about in the context of the "greenhouse effect" to explain the damage being wreaked on our planet.
Without the greenhouse effect the Earth's surface would be an average of about 60 degrees Fahrenheit cooler, and therefore unlivable.
The effect allows gases in but keeps heat from escaping from the earth, like the glass walls of a greenhouse.
However, over the past century humans have aggravated the greenhouse effect by dramatically increasing the level of carbon dioxide in the atmosphere.
Human sources of CO2 come from activities such as deforestation and the burning of fossil fuels like coal, oil and natural gas.
Since the Industrial Revolution the amount of carbon dioxide in the atmosphere has rocketed by a third.
This rapid rise has had a direct impact on the Earth's average temperature, with potentially catastrophic consequences.
What effect is it having on earth?
The rise in the average global temperature has already had a demonstrable impact.
Greenhouse gases are believed to be higher now than in the last 650,000 years.
Melting glaciers, rising sea levels and dying cloud forests have all been directly linked to climate change.
Humans too are already suffering directly - with deadly heatwaves and catastrophic flooding becoming a regular occurrence.
The West Antarctic ice sheet used to be stable a few decades ago but new evidence shows that up to a quarter of it is now thinning.
In the worst hit locations, more than 100 metres of ice thickness has been lost.
Completely losing the West Antarctic ice sheet would result in global sea levels rising by about five metres.
This amount of sea level rise would drown coastal cities around the world.
Scientists think that sea levels are now rising at the extreme end of what was predicted to happen gradually just a few years ago and current losses of ice are said to be doubling every decade.
Rising sea levels – what's the problem?
Here's what you need to know...
- The global sea level has been gradually rising over the past century
- Sea levels rise due to two main reasons
- The first is thermal expansion – as water gets warmer, it expands
- The second is melting ice on land, adding fresh water into seas
- This has a cyclical effect, because melting ice also warms up the planet (and oceans), causing more even ice to melt and boosting thermal expansion
- It's currently rising at a rate of around 0.3cm per year
- The sea is huge, so that might sound harmless
- But rising sea levels can have a devastating effect over time
- Low-lying coastal areas can disappear completely, even putting areas of the UK at risk
- It can also mean sea storms and tsunamis can have a more devastating effect, reaching further in-land than they would have previously
- There's also an increased risk of flooding
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What is the world doing about it?
In December 2015 world leaders reached a landmark agreement to combat climate change.
The Paris Agreement built upon the UN Convention and brought all nations together for the first time in the battle against a common enemy.
Central in the treaty was the decision to strengthen the global response to the threat of climate change by keeping a global temperature well below 2 degrees Celsius above pre-industrial levels and to limit the increase even further to 1.5C.
This research has been published in the journal of Geophysical Research Letters.
It describes how scientists used satellites images to compare the sizes of ice sheets from 1992 to 2017 with weather information.
Professor Andy Shepherd, who led the study, said: "From a standing start in the 1990s, thinning has spread inland progressively over the past 25 years – that is rapid in glaciological terms.
"The speed of drawing down ice from an ice sheet used to be spoken of in geological timescales, but that has now been replaced by people’s lifetimes."
Shepherd also stressed that some glaciers, such as the Pine Island and Thwaites glacier basins, are past the halfway point of melting.
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This new work should help researchers to more accurately pinpoint where sea levels will rise so appropriate preparations can be made to try and save affected areas.
The underside of glaciers are thought to be melting because the sea is too hot and not even snowfall can counteract the damage.
There are other indications that the treaty is creating positive change. France has announced plans to ban all petrol and diesel vehicles by 2040, while Norway has said it will ban the sale of petrol- and diesel-powered cars by 2025.
In June 2018 the Netherlands passed a bill mandating a cut by 2050 its 1990 greenhouse-gas emissions level by 95 per cent—exceeding the Paris Agreement goals.
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