Bees and the changing climate

Bee populations and the changing climate
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Norman Carreck, Science Director of the International Bee Research Association, spoke to SciTech Europa Quarterly to outline some of the environmental challenges facing bee populations.

Human activity is having a substantial impact on the natural world. Recently, the United Nations’ Climate Panel announced that they were 95% certain that humans are the ‘dominant cause’ of global warming since the 1950s. And, alongside this, it is widely held that climate change is having adverse effects on bee populations around the world, as warmer and drier conditions cause extinctions and also drive populations of both plants and insects north.

Speaking to SciTech Europa Quarterly, Norman Carreck, Science Director of the International Bee Research Association, outlined some of the environmental challenges facing bee populations, where he also emphasised how climate change discussions should take into account not only the effects on bee populations but also on other plants and animals, too.

It has been argued that animal pollination of both wild and cultivated plant species is under threat as a result of multiple environmental pressures acting in concert. What do you feel are the biggest environmental pressures at force here? How much of an impact is climate change having to pollinator populations in Europe?

The biggest threat to bee populations is environmental change in general and within that, the biggest factor is changes in land use. In Europe, this includes the intensification of farming over the last 70 years or so (since the Second World War), the removal of hedgerows, changes in the types of crops being planted, and urban development. Together, the impact of this is essentially a lack of food for bees and fewer nesting sites for wild bees.

Alongside this, there are many other factors which need to be taken into consideration, such as pests and diseases, and while we know a lot about the pests and diseases of honey bees, we know much less about the pests and diseases of other species. Then, of course, there is the issue of pesticides, which is effectively a result of agricultural intensification. Then, amongst the other environmental factors, climate change is clearly a serious problem.

However, the extent to which climate change is having an impact depends on the bee species in question. The western honey bee, Apis mellifera, for instance, is incredibly versatile and will feed on wide variety of sources. They also have a huge geographical range and were quite widely distributed in Africa, Europe, and parts of Asia originally. But, of course, human activities have meant that it has now spread elsewhere. Indeed, the number of honey bee colonies in many places is purely determined by man.

The honey bee is also incredibly resilient to climate change, and it is very mobile on its own (while humans have made it even more mobile), and it can cope with most of the challenges it experiences. As such, it is likely that this species of bee will experience both positive and negative effects of climate change. Yet, while there is a distinct sense that the honey bee will cope relatively well with climate change, that may not apply to other bee species in the same way, and we know much less about them.

For example, bumble bees are temperate creatures which don’t cope well with very hot temperatures; they literally overheat. A number of research papers published in northern Europe have presented evidence that the southern boundary of the distribution of certain bumble bee species is moving northwards, and, moreover, that there have been local extinctions of bumble bees in various places that have become warm and drier.

Just because bees can fly doesn’t simply mean that they will move to somewhere more suitable when conditions change. Indeed, the evidence seems to be that they are not moving northwards as temperatures increase. Or, at least, they are not moving northwards at the necessary speed. As such, they are becoming extinct in places where it is now too warm and dry for them; their distributions are becoming squeezed. While we don’t have a lot of information on this as yet, it would make sense that this is also happening to various solitary bees, too.

Is there more that could be done to adapt their environment rather than expecting them to migrate north as temperatures warm?

It is very difficult to know what can be done. In places where natural food is becoming scarcer for bee populations, then one can grow things that provide alternative food for them.

And we must also remember to think of the plants as well as the bees. Plant distributions are clearly changing due to climate change, and while plants do move, they move even slower than flying insects.

There are thus other more complex problems which need to be addressed too. In that if the phenology of plants is changing with climate change, from a crop pollination point of view, then this could mean that a crop flowers earlier before the bees are there to pollinate them, or vice versa. And this is a far more serious a problem when we think about very rare wildflowers and very rare bees.

Some very rare bees are extremely specific in what they feed on. There are a whole range of solitary bees that will only feed on one type of pollen, so clearly if the timing of the plants is changing due to global warming, and the plant no longer flowers at the time the bee is around, then it can affect both the bee and the plant, because the bee will starve and the plant may not get pollinated, and therefore its population will decline.

Of course, if it is a perennial plant it could go on not developing seeds for a very long time and if by then its only pollinator is extinct, then the effects for both species are dire.

There are many other examples of very delicate and subtle things like this, most of which we really lack detailed knowledge about as this remains a very under-researched area.

How can we try to fill that knowledge gap? Is there a lack of funding or just a lack of appetite to research these areas?

It is unclear as to why research in these areas isn’t as popular as it could or should be. Funding available for the various aspects of climate change is quite easy to access, and has been over the last ten or fifteen years. And yet this remains an area that not many bee researchers are approaching.

Do you feel that the effects on pollinators and their environment are high enough on the agenda when it comes to discussions about climate change? How would you like to see this change?

One of the problems here is perhaps that people have made the wrong argument. For instance, social media often sees a supposed quote from Albert Einstein that if bees disappear then people have around four years to live. There is absolutely no record that Einstein ever said that, and, what is more, the statement simply isn’t true: most of the world’s major staple food crops are wind pollinated.

But of course, insect pollination is incredibly important, because insects pollinate the things that make eating pleasurable. Fruits and nuts, chocolate and coffee and things like that, all rely on insect pollination. The world would not starve without insects, but I think it would be a very dull place.

The argument therefore needs to be made from the pollination point of view. Additionally, however, we must also understand that the pollination of the many other wild plant species which we don’t necessarily eat but that are equally important for their own sake also deserve attention and it is these that perhaps tend to get ignored in the major arguments and conversations.

How much of a focus does International Bee Research place on climate change, and do you anticipate this growing moving forwards?

It is certainly something we clearly bear in mind. However, upon receipt of your questions I thought about when we last received an article on bees and climate change for one of our journals, and I am afraid it has been quite some time.

I would certainly be keen for the issue of bee populations to be pushed higher up the agenda in terms of discussions about climate change, and this comes back to the fact that not much research is happening in this area at the moment.

I am not entirely sure why it has such a low profile, and it should perhaps have a higher profile in the general discussions about climate change. Clearly, there are two issues here: one concerns the pollination of crops that improve the diversity of the food we eat, and the other is the conservation of plants and animals for their own sake, which I think is often ignored in climate change discussions in general.


Norman Carreck

Science Director

International Bee Research Association


This article will appear in SciTech Europa Quarterly issue 26, which will be published in March, 2018

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