Nature on the move

I've handed the reins of my blog over to Mark Avery for most of June. Mark's sharing the successes and challenges of saving nature around the world in the run up to the Rio+20 Earth Summit.

If you have had an eye on nature for the last few decades then you are likely to have noticed changes around you. The chiffchaffs that I used to hope to hear before my birthday at the end of March I now hear a couple of weeks earlier. Many butterflies are spreading north in the UK, for example marbled whites and speckled woods, even though in some cases their populations are declining in numbers.  My walks in rural Northamptonshire are now quite likely to include sightings of little egrets, which would have been very rare sightings even 20 years ago.

Observations reveal to us the biological impacts of a warming global and local climate; spring events nudge a little earlier and southern species spread north. 

Nature is on the move in space and time, across the world, because of climate change and we can see signs of those changes in the nature around us – and in the fact that you need to cut the grass later and later each autumn as the growing season lengthens.

There is already plenty of evidence that these climate-induced changes may not all be benign. Some summer migrants, unlike my chiffchaffs, have not shifted their arrival dates forward, we don’t really know why not. And, looking across Europe as a whole, those species, such as wood warblers, that have not advanced their arrival dates are declining rapidly. It may be, and the RSPB is looking at these issues, that somehow, some species are a bit stuck – they can’t get back to their breeding grounds any earlier and so when they do return they find that they are missing important flushes of insect life which are now happening a little earlier in the year.

And many species which are moving north are also losing ground on the southern edge of their range. Take the Dartford warbler as an example. This resident warbler has spread north in recent decades, and we expect to see that continue, but at the southern edge of its range in Europe, which holds many more Dartford warblers, the Spanish and Portuguese see declines in numbers. Will northern England, Ireland and Denmark really provide enough suitable habitat for Dartford warblers to compensate for the losses further south in their range? 

Northern species don’t have as much scope to move further north – if you keep pushing polar bears north then they end up all trying to live at the North Pole, and where do Orkney and Shetland’s whimbrels go – there’s a lot of sea and not much land north of them?

Species living on low-lying coasts, whether they be redshank on Essex saltmarshes or tigers in the Sunderban mangrove ecosystem will be threatened by rising sea levels. Species that live at high altitudes may find their habitats are squeezed out whether they be the already extinct golden toad of Costa Rica or the dotterel of our Scottish mountain tops.

Climate change throws challenges at all life on the planet – our species and all other species too. As many as a third of all species on Earth may be committed to extinction by climate change by the end of this century.Will we rise to the challenge and will this month’s Rio+20 summit help move things along enough? And should I feel pleased or sad when I hear an early chiffchaff?

The UK should be leading the move to a fair and green economy, not going backwards on its commitments. We are asking as many MPs as possible to sign the Stop Climate Chaos Coalition’s Rio Declaration to commit to a sustainable future. Step and ask your MP to support the Rio-UK Declaration.

Dr Mark Avery is a former Conservation Director of the RSPB and now is a writer on environmental matters. We’ve asked Mark to write these 20 essays on the run up to the Rio+20 conference.  His views are not necessarily those of the RSPB.  Mark writes a daily blog about UK nature conservation issues.