Asylum seeker numbers in Europe could rise dramatically due to climate change, even in optimistic warming scenarios, according to new research.

Researchers at Columbia University found a worst-case scenario for climate change could increase the number of asylum seekers in EU countries in 2100 by as much as three times the number seen at the beginning of the century.

The migrant crisis, which came to the world’s attention in 2015, saw increasing numbers of people seeking asylum in Europe.

Many people leave their home countries owing to environmental changes like drought, and such changes are often exacerbated by global warming.

Migrants ride railroads to seek better future Show all 10 1 /10 Migrants ride railroads to seek better future Migrants ride railroads to seek better future Habib, 22, from Algeria with his friends on an abandoned railway wagon. They boarded a freight train in an effort to cross the Greek-Macedonian border without documents. They were arrested in Macedonia and returned back to Greece Reuters Migrants ride railroads to seek better future A migrant jumps on a freight train in an effort to cross the Greek-Macedonian border in the northern city of Thessaloniki, Greece Reuters Migrants ride railroads to seek better future An Algerian migrant has a picture of fellow migrants in Macedonia. According to the migrant, his mobile phone was broken by Macedonian police when he was arrested and returned to Greece Reuters Migrants ride railroads to seek better future Algerian migrants are seen on a freight train before its departure in the northern city of Thessaloniki Reuters Migrants ride railroads to seek better future Anise, 21, an English teacher from Algeria, rests in an abandoned railway wagon used as a shelter by stranded migrants in Thessaloniki Reuters Migrants ride railroads to seek better future Algerian migrants lay on the railway tracks as they wait for a freight train to depart Reuters Migrants ride railroads to seek better future An Algerian holds up his injured hand. He was injured in his effort to jump on a freight train Reuters Migrants ride railroads to seek better future Migrants walk between railway wagons in the northern city of Thessaloniki Reuters Migrants ride railroads to seek better future An Algerian smoking inside an abandoned railway wagon used as a shelter by stranded migrants Reuters Migrants ride railroads to seek better future A migrant with his belongings waiting for a freight train to depart Reuters

“Europe is already conflicted about how many refugees to admit,” said Professor Wolfram Schlenker, an economist at Columbia University who co-authored the new study, which was published in the journal Science.

He noted that though the direct effects of climate change tend to be felt more in “poorer countries in hotter regions”, Europe will feel the indirect effects as a result of asylum seekers fleeing those countries.

The study by Professor Schlenker and his colleague Anouch Missirian specifically suggested the less suitable a country’s temperature was for growing crops, the more likely its inhabitants were to migrate.

This meant migration might be particularly pronounced in countries that already have hot climates.

The researchers used past data on weather variations around the world and asylum seekers in Europe to estimate how future climate change will impact the flow of refugees.

The researchers looked at how weather variations in 103 “source” countries for refugees – ranging from Bangladesh to Eritrea – compared to asylum applications to the EU.

Between 2000 and 2014, there was an average of 351,000 asylum applications per year from people in the countries studied.

The researchers then used projections of future warming combined with asylum application data to estimate changes in the flow of migrants over the course of the century.

They found that even under a “slow warming” scenario, in which future greenhouse gas emissions go down, asylum applications to the EU could increase by as much as 28 per cent by 2100 – an additional 98,000 asylum applications per year.

Under a fast-warming scenario, in which emissions continue to increase, the researchers predicted an extra 660,000 applications per year, amounting to triple the number at the beginning of the century.

“It is often argued that climate change is exacerbating existing threats to society as well as generating new ones,” said Dr Emily Shuckburgh, a climate scientist at the University of Cambridge who was not involved with the study.

“This study provides compelling evidence linking past asylum applications received by EU member states to the climate of the country of origin,” she said.

Though Professor Schlenker emphasises that there are many factors involved in migration and asylum seeker applications, this work indicates the importance of strategies to reduce climate change.

Specifically, his analysis indicates that the pressures associated with a large influx of asylum seekers could be alleviated if nations work to limit global warming to below 2C, as per the Paris climate agreement.

“If you stay within the 2C increase, the increased flow is not as large,” he said.

There has been significant backlash in many European countries to the influx of migrants in recent years.

Though nations like Germany have taken in significant numbers of asylum seekers, the unprecedented numbers of people making applications mean nations have often been unprepared for the situation.

Professor Schlenker suggested this kind of work could help develop an “early warning system” to help prepare for influxes of people.

“We will need to build new institutions and systems to manage this steady flow of asylum seekers,” said Professor Solomon Hsiang, a researcher working in this field at the University of California, Berkeley, who was not involved in this study.

Professor Hsiang described these findings as an “incredibly important” wake-up call.

“As we have seen from recent experience in Europe, there are tremendous costs, both for refugees and their hosts, when we are caught flat footed,” he said.