YOU would be forgiven for not knowing that there are two large United Nations environmental events happening this year. The UN Climate Change Conference (COP 26) in Glasgow, UK, is receiving a huge amount of media attention; the UN Biodiversity Conference (COP 15) in Kunming, China, much less so. At least, outside 91av.

This is a source of frustration to us ecologists, but it is fairly typical: the climate emergency often overshadows the ecological emergency, even though the two overlap both in their causes and their solutions.

Although ceasing the extraction of fossil fuels is a priority, if we are going to reverse the effects of climate change we need nature-based solutions, built on conservation of biodiversity, to capture the carbon dioxide from the atmosphere. Pollinators are crucial to this, but their numbers are declining, some species have gone extinct and others are critically endangered.

Around 75 per cent of the world’s main types of crops rely on pollinators. Without them, our diets and farmers would be poorer. But their value in combating climate change is often overlooked. Almost 90 per cent of the 352,000 species of flowering plants are pollinated by insects and vertebrates such as birds and bats. As such, pollinators ensure the continuation of plant populations that lock up carbon in their woody stems, roots, bulbs and tubers. The best way to restore natural habitats to help fight global warming is through natural regeneration from seeds, and for that we need pollinators.

But this may not be the most important role of pollinators in relation to climate change; how they affect soils may be more critical. When a pollinator visits a flower it sets in motion a chain of events that leads not just to seeds, but also to a series of structures that support plant reproduction. These include woody fruit casings that protect the developing embryo, as well as dispersal structures such as the wings of sycamore seeds. All of these contain a very high proportion of carbon. Once they have fulfilled their function, they fall to the ground where they enter the soil as a source of locked-in carbon.

Soils are the world’s second-most important carbon store, and much more important than the vegetation that they support. In fact, three-quarters of terrestrial carbon accumulates in soils. Only the oceans contain more carbon by mass.

How much carbon enters the soil thanks to the activities of pollinators? We have no idea as it hasn’t been measured. Ecologists studying forest carbon dynamics use fine nets strung between stakes to measure the “litter” that falls from trees each year. The contribution of reproductive litter, as opposed to leaves or twigs, isn’t always calculated, but when it is values of 10 to 20 per cent of the total litter are typical, depending on the type of plant.

We have limited understanding of what happens when this material enters the soil. A large number of seeds are stored in the soil and they can be persistent, and reproductive litter can be very woody compared with leaves, and thus their carbon storage capacity may be greater.

For these reasons, it is vital that we pay more attention to international agreements, such as the Convention on Biological Diversity, and enact policies that safeguard pollinators, for example by banning harmful pesticides and creating larger protected areas. This requires action now at all levels, from governments to conservation groups, to create and restore habitats in which pollinators can thrive.

Drawing down carbon from the atmosphere and sequestering it requires multiple approaches; there is no single solution. Without pollinators as allies, reversing the effects of climate change will be much harder.

It is the second of these duties which led to my original question,
and raises another: What is it that changes an undergraduate being taught
into a postgraduate who is teaching? The obvious answer is, of course, ‘a
degree’. However, my knowledge of environmental biology is no greater now
than it was just before I sat my finals (in fact, it is somewhat less, as
my ability to retain crammed knowledge is less than perfect). So I was just
as capable (or otherwise) of teaching first-year students when I was in
my final year as I am now. So why didn’t I?

The point I am trying to make is this. It would seem to make good sense
to exploit the accumulated knowledge and ability of final-year students,
and use them as teaching assistants for tutorials, laboratory classes, field
work and so on. The academic institution would gain from having more teaching
staff; the higher ratio of teaching staff to students would benefit the
first-year undergraduates; and the teaching assistants would accrue valuable
experience, as well as having the chance to reinforce and re-evaluate subjects
previously studied. Any degree course works on the principle of successive
topics building upon knowledge previously gained, so this would be particularly
useful.

Of course, not everyone has an aptitude for teaching, but such a scheme
would build confidence, which is an important component of communicating
knowledge. The ‘undergraduate teaching assistants’ would all be volunteers,
but I believe that many final-year students would jump at the chance to
take an active part in the teaching process. Motives for such enthusiasm
would vary, from the altruistic (‘helping the poor unfortunates to navigate
the treacherous reefs of their first year at college’) to the plain selfish
(‘bit of an ego boost, and the chance to meet new people’).

Another benefit would be a strengthening of course identity. Modular
degrees, such as the one I have completed, are often lacking in this respect,
and it is possible to complete your course without ever meeting some of
the people who are ostensibly studying for the same qualification. When
the pass list for my course was published this summer, there were names
there which I had never even heard of.

Undergraduate teaching assistants would seem to be a good idea. Anyone
willing to try it?