CLIMATE CHANGE 2

Hot or cold?

An anomaly of the projections of climate change science that shows our planet warming at an alarming rate is that the UK, rather than warming, could become much colder. The reason for this is that the processes that drive the Gulf Stream across the Atlantic to our shores bringing warm water and associated warm air to us, could cease to function. This would be what is known as a shut-down in thermohaline circulation of an ocean current. I must immediately point out that there is much debate and disagreement about this – nothing new there! Whether or not the Gulf Stream will shut down is moot, but there is evidence that it is slowing. The Gulf stream is driven by movements of water due to evaporation and changes in salinity/density so the concern is that the increase of fresh water from melting ice sheets and glaciers and increased precipitation pouring into the sea at the northern end of the gulf stream will adversely affect/are already adversely affecting the dynamics of the current, particularly as the salinity and evaporation decrease resulting in the water being less dense, so not descending and driving the pump. Please keep up! Yes, it is complicated and I also confess to simplifying a complex phenomenon with many variables, but I am trying to present just the gist of it.

It is argued that changes in the Gulf Stream caused previous ice ages and, if so, we are in danger of another, at least in NW Europe. More research is needed, and it is encouraging to see the launch of the RRS Sir David Attenborough (and its long range, technically advanced research submarine, the famous Boaty McBoatface). This spectacularly equipped research vessel will help us understand what is going on in the polar seas.

Supposing that, instead of warming, our climate becomes much colder, what changes might we see and how might wildlife react? The answers depend greatly on the magnitude and rapidity of the changes. A sudden change over a few years to much colder winters (think Moscow) would be ecologically devastating as much of our vegetation cannot withstand very long periods of extremely hard frost and it takes decades for new cold-tolerant vegetation and the fauna associated with it to establish. Conifers (spruce, pine) could come to dominate woods & forests, probably with stands of silver birch, but oak would survive if not too cold. An ice sheet, though, would effectively destroy all.

Boreal forests are rich in species, although they are very different from our temperate ones. Grasslands would be more alpine in nature – you can see something like this on the very top of Snowdon. Indeed, exploring the higher altitude ecosystems of Europe is probably the best way to gain an impression of what much of the semi-natural parts of the lowland UK could look like in a colder climate.

Will our greenspaces look more like this continental alpine one if the Gulf Stream feeds us less warm air? (NB. It is covered in deep snow all winter!) Photo be the author.

Betts Ecology will continue to strive to be at the forefront of applying scientific knowledge in the battle against climate change in the management of our sites.

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