How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

The surge of people fleeing to Europe from the Middle East highlights how quickly mass migrations can occur. It may also offer a glimpse of what’s to come as climate change makes some regions around the world unlivable, according to a leading researcher on the human effects of climate change.

Frank Biermann, a professor of political science and environmental policy sciences at VU University Amsterdam, led researchers in the Netherlands five years ago in a study that warned there may be as many as 200 million climate refugees by 2050. That staggering number first arose out of research in 1995, and it has always been controversial. The study Biermann led in 2010 recommended the creation of an international resettlement fund for climate refugees.

Today’s migrant crisis may be due in part to climate change, Biermann said in an interview with InsideClimate News. Syria, where 7.6 million people are displaced inside the country and another four million are seeking asylum elsewhere, a severe drought plagued the country from 2006-09. A recent study pinned the blame for that drought on climate change, and the drought has been cited as a contributing factor to the unrest there. Millions of additional refugees may need to leave their homes in coming decades as a result of a changing climate, Biermann said.

As Biermann discussed the issue, his 9-year-old daughter was preparing a welcome package that included toys, books, and a note with her home phone number that will be delivered to an immigrant girl her own age.

The interview has been edited for length and clarity.

InsideClimate News: The ongoing uprising in Syria was preceded by the region’s most severe drought on record. Are the Syrians now moving into Europe climate refugees?

Frank Biermann: Many of these refugees come from countries that are affected by climate change, there is no doubt about that, even though I would not make necessarily any causal link between climate change and the Syrian or Iraqi crises. Of course, there are many other reasons responsible for the war and civil strife in these countries.

My argument in the paper from 2010 has been that over the following decades and the second half of the century we can expect much more migration to happen due to the impacts of climate change. That is the expectation from many models that have to do with sea level rise, land degradation, desertification, water shortages, and a number of other issues that historically have been causes for migration. It’s quite obvious in the case of sea level rise where coastal defenses are technically not feasible or too expensive. In such cases people will have to move and resettle somewhere else.

ICN: How does what we are seeing now compare with what is likely to come?

FB: There are a number of scenarios in the literature that are predicting vast numbers of climate refugees in the future, up to 200 million people by 2050. Many of these projections and scenarios are slightly outdated. The current debate is a bit more careful or optimistic because these newer scenarios are all based on assumptions about the adaptive capacities of these countries and the severities of climate change impacts and also on human behavior. Many people would now argue that the numbers that have been published especially in the 1990s and early 2000s are too pessimistic.

On other hand, it’s quite obvious that there are certainly areas, especially low-lying coastal areas, that quite likely will be severely affected from sea level rise. You can look at how many people are in low-lying areas in Bangladesh, in Egypt, in Vietnam, and the eastern part of China. There are millions of people who are in these kinds of areas, and the same is also true for land degradation, desertification, and water shortages. It is likely that a lot of this migration will be internal migration within the country; it’s not necessarily to be expected that everyone will go on a boat to Europe.

ICN: The 200 million figure you cite in your 2010 study has been controversial since Norman Myers of Oxford University first proposed it in 1995. The Biodiversity Institute at Oxford said the figure is “widely viewed as lacking academic credibility,” and Stephen Castles from Oxford’s International Migration Institute said Myers’ objective was to “really scare public opinion and politicians into taking action on climate change.” Does what we are seeing now change things?

FB: I think it’s much more complex than thought originally. If climate change continues to develop the way it is predicted to develop, then there is a high likelihood that more people will be negatively affected in their livelihoods, and it’s likely that more people will have at some point to relocate and resettle.

Climate change has the potential of increasing all refugee crises and of creating new refugee crises. It is never a one-to-one relationship that people are leaving just because of climate change. It is always linked to all kind of other factors—economic factors, social factors, political factors, religious factors—but all these factors that are supporting civil war and migration might be increased by climate change.

If we don’t stop climate change, then what we see right now is just the beginning. It has the possibility to turn into a major driver of migration movements, and this is one of the many, many arguments of why we have to stop climate change.

ICN: What needs to happen to protect future climate refugees?

FB: We see a direct moral and legal connection between rich countries and the impacts of climate change. The majority of people negatively affected by climate change live in poor countries where they have almost nothing to do with the causation of the problem.

We came up with a proposal to have a separate fund, the Climate Refugee Protection and Resettlement Fund, to address this particular problem. The bottom line is when you are sitting in Tuvalu and you have to leave your island, and you are certainly not responsible for climate change, then you can have a moral and legal right to request compensation and assistance from rich countries.

ICN: Since your 2010 study, the United Nations Framework Convention on Climate Change launched the Green Climate Fund to do much of what you describe. The initial plan was to have wealthy countries donate $100 billion a year by 2020, but so far only $10.2 billion has been pledged. Is this enough?

FB: The original numbers in the $100 billions are realistic, but I think definitely more investment is needed.

This post originally appeared at InsideClimate News.