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Climate change is set to cause major changes across the world: sea levels will rise, food production could fall and species may be driven to extinction.

The UN has warned that the world needs to limit climate change to below 1.5C above pre-industrial levels. But scientists say that keeping to the 1.5C target will require "rapid, far-reaching and unprecedented changes" in all aspects of society.

So how warm has the world got and what can we do about it?

1. The world has been getting hotter

The world is now nearly one degree warmer than it was before widespread industrialisation, according to the World Meteorological Organization (WMO).

The global average temperature for the first 10 months of 2018 was 0.98C above the levels of 1850-1900, according to five independently maintained global data sets.

How years compare with the 20th Century average 2019 10 warmest years 10 coldest years 20th Century average Hotter Colder Months J F M A M J J A S O N D Source: NOAA Replay

(If you can't see this chart tap or click here)

The 20 warmest years on record have been in the past 22 years, with 2015-2018 making up the top four, the WMO says.

If this trend continues, temperatures may rise by 3-5C by 2100.

One degree may not sound like much, but, according to the IPCC, if countries fail to act, the world will face catastrophic change - sea levels will rise, ocean temperatures and acidity will increase and our ability to grow crops, such as rice, maize and wheat, would be in danger.

2. The year 2019 set all sorts of records

Almost 400 all-time high temperatures were set in the northern hemisphere during the summer of 2019.

Records were broken in 29 countries for the period between 1 May and 30 August. A third of the all-time high temperatures were in Germany, followed by France and the Netherlands.

These European records were set amid heatwaves across the continent that sent temperatures soaring in June and July.

Over the period shown on the map below (May to August 2019), the yellow dots show where a heat record was broken on a given date, pink indicates places that were the hottest they had ever been in the month shown, and dark red represents a place that was the hottest since records began.

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More than 30 all-time records were broken in the US, according to the Berkeley Earth data. In Japan, where 11 people died as a result of the summer heatwave, 10 all-time temperature highs were set.

3. We are not on track to meet climate change targets

If we add up all the promises to cut emissions made by countries that are party to the Paris climate agreement, the world would still warm by more than 3C by the end of this century.

Over the past few years, climate scientists have shifted the definition of what they believe is the "safe" limit of climate change.

For decades, researchers argued the global temperature rise must be kept below 2C by the end of this century to avoid the worst impacts.

Countries signing up to the Paris agreement pledged to keep temperatures "well below 2C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5C".

But scientists now agree that we actually need to keep temperature rises to below 1.5C.

4. The biggest emitters are China and the US

The countries emitting the most greenhouse gases by quite a long way are China and the US. Together they account for more than 40% of the global total, according to 2017 data from the European Commission's Joint Research Centre and PBL Netherlands Environmental Assessment Agency.

US environmental policy has shifted under the Trump administration, which has pursued a pro-fossil fuels agenda.

President Donald Trump has begun the process of withdrawing the US from the Paris climate change agreement.

Mr Trump said the deal struck in 2015 would disadvantage US businesses and workers.

5. Urban areas are particularly under threat

Almost all (95%) of cities facing extreme climate risks are in Africa or Asia, a report by risk analysts Verisk Maplecroft has found.

And it's the faster-growing cities that are most at risk, including megacities like Lagos in Nigeria and Kinshasa in the Democratic Republic of Congo.

Some 84 of the world's 100 fastest-growing cities face "extreme" risks from rising temperatures and extreme weather brought on by climate change.

6. Arctic sea ice is also in danger

The extent of Arctic sea ice has dropped in recent years. It reached its lowest point on record in 2012.

Sea ice has been reducing for decades, with melting accelerating since the early 2000s, according to the UK Parliament's Environmental Audit Committee.

The Arctic Ocean may be ice-free in the summer as soon as the 2050s, unless emissions are reduced, the committee has said.

The extent of Arctic sea ice in 2019 was tied with 2007 and 2016 as the second lowest on record. The maximum extent, reached in March 2019, was tied with 2007 as the seventh lowest in the 40-year satellite record.

7. We can all do more to help

While governments need to make big changes - individuals can play a role too.

Scientists say we all have to make major changes to our lifestyles, in order to avoid severely damaging climate change.

The IPCC says we need to: buy less meat, milk, cheese and butter; eat more locally sourced seasonal food - and throw less of it away; drive electric cars but walk or cycle short distances; take trains and buses instead of planes; use videoconferencing instead of business travel; use a washing line instead of a tumble dryer; insulate homes; demand low carbon in every consumer product.

One of the biggest ways to reduce your environmental impact on the planet is to modify your diet to include less meat - according to recent studies.

Scientists say we ought to eat less meat because of the carbon emissions the meat industry produces, as well as other negative environmental impacts.

A recent study published in the journal Science highlighted a massive variation in the environmental impact of producing the same food.

For example, beef cattle raised on deforested land produces 12 times more greenhouse gas emissions than those reared on natural pastures.

Crucially, the analysis shows that meat with the lowest environmental impact still creates more greenhouse gas emissions than growing vegetables and cereal crops in the least environmentally-friendly way.

But as well as altering our diets, research suggests that farming practices need to change significantly to benefit the environment.

By Nassos Stylianou, Clara Guibourg, Daniel Dunford, Lucy Rodgers, David Brown and Paul Rincon

Correction 24 February 2020: A previous version of this story said that "the single biggest way to reduce your environmental impact on the planet is to modify your diet to include less meat". This has been amended to now refer to "one of the biggest," taking account of different individual lifestyles and circumstances. We have also replaced the in-line link with a research article on 'The global impacts of food production'.