Introduction
Climate change is a large-scale, long-term shift in the planet’s weather patterns and average temperatures. It is driven by emissions of carbon dioxide (CO2) and other potent greenhouse gases into the atmosphere. Climate change has occurred throughout the Earth’s history due to natural causes. However, there is overwhelming scientific evidence that the warming currently being observed is a result of increased greenhouse gas emissions from human activity.
The UK Committee on Climate change states:
Global CO2 emissions from human activity have increased by over 400% since 1950. As a result, the concentration of CO2 in the air has reached more than 400 parts per million by volume, compared to about 280 parts per million in 1750 (around the start of the Industrial Revolution).
The chart below from NASA shows current CO2 levels compared to natural changes over the past 400,000 years.
Unseasonal weather and climate change
This time last year, much of the UK was covered in deep drifts of snow, and experienced sub-zero temperatures for nearly 10 days. In contrast, this year, February has seen temperatures of over 20°C, and is expected to be one of the warmest Februaries since records began.
On 21 February, Aboyne in Aberdeenshire set a new February temperature record of 18.3°C, beating the previous record of 17.9°C set in 1897. Scientists refer to these events as temperature anomalies.
At this time of year it is more common to experience cold air drawn down from the north. According to the Met Office, the average February temperature in Aboyne from 1981-2010 was 6.5°C.
After the recent warm weather, many people are asking whether this unseasonal warmth is linked to human caused climate change.
What does the science say?
Dr Friedericke Otto, from the Environmental Change Institute at Oxford University stated:
I am very confident […] that there’s an element of climate change in these warm temperatures.
But climate change alone is not causing it. You have to have the right weather systems too.
James Screen, Professor in Climate Science at the University of Exeter noted that:
It’s very hard to say that a couple of days of good weather is because of climate change. But what we do know, based on overwhelming scientific evidence, is that climate change is only pushing in one direction.
Overall, climate change is meaning that hot extremes are getting more likely and cold extremes are getting less likely.
Long-term trends
Global average surface temperature has increased by about 1°C since the 1850s. Each of the last three decades has been successively warmer than any other preceding decade, and 16 of the 17 warmest years on record have occurred since 2001. Ed Hawkins, Professor of Climate Science at the University of Reading presents the following:
The last four years have been the four warmest on record for the planet #climatechange #StateOfClimate pic.twitter.com/0XG1xhCwnU
— Ed Hawkins (@ed_hawkins) November 29, 2018
Intergovernmental Panel on Climate Change Fifth Assessment Report showed that changes in many extreme weather and climate events have been observed since about 1950. There is evidence of human contribution to changes in temperature extremes, heavy rainfall events, and an increase in extreme high sea- levels in a number of regions. The weight of evidence for a human fingerprint in extreme weather events is increasing.
The general trend in the UK is for winters to become warmer and wetter, and for spring to come earlier. Weather extremes, including storms, rainfall and heatwaves will become more likely.
Impacts of these extremes
As a result of these extremes, wildfires like those recently witnessed on Arthur’s Seat, and Saddleworth Moor may become more likely. David Demeritt, Professor of Geography at Kings College London called the fires “unseasonable”, and stated:
Landscape fires in Britain happen disproportionately in the Spring, because on the moors and in the forest, you have no leaf cover.
Sticks and leaf litter dry out. And because this has been a relatively dry winter, there’s more of that fuel on the ground – everything has dried out early.
Significant ecological damage is not expected because soil is wetter in winter, despite well below average rainfall.
The SPICe Blog, Wildfires – a future burning issue? explores these in more detail.
Other less obvious, but potentially more serious impacts of warm spells in winter include hedgehogs, reptiles and insects coming out of hibernation early, but then struggling to find food when cold weather returns (as expected across Scotland this week), forcing worms and slugs to disappear out of reach.
Honey bees were spotted in Butterstone, Perthshire on 21 February:
Crivens ! 14 degrees in Butterstone today and the #honeybees are out in numbers. Crank up the volume and listen to the buzz. Not a common sight in #February in Scotland – and a little troubling…. #climatechange @SNHnortheast @nature_scot pic.twitter.com/DrfBxqYqUx
— brendanturvey (@brendan_turvey) February 21, 2019
Adapting to climate change
The Scottish Government’s Climate Change Adaptation Programme (SCCAP) was published in 2014, and annual progress reports have been published since 2015.
The Programme aims “to increase the resilience of Scotland’s people, environment and economy to the impacts of a changing climate”, and was designed to address over 130 climate impacts through around 150 individual policies and proposals spanning three themes: natural environment; buildings and infrastructure; and society. It aims to:
- Help Scotland adapt to the effects of climate change.
- Create a more resilient country for us to live and work in.
- Help to protect Scotland’s much loved natural environment.
The UK Committee on Climate Change’s assessment of the SCCAP considered that it was “a significant first step to bring together existing policies and activities into a more coherent programme”, however “it could be improved in terms of its coverage, governance and impact”, and “evidence of progress being made is mixed”, with “insufficient evidence to judge progress in many of the areas assessed”.
The second SCCAP is due to be published later this year, and is currently being consulted on.
Current Scottish Parliament Action
The Scottish Parliament’s Environment Climate Change and Land Reform Committee has today published its long awaited Stage 1 Report on the Climate Change (Emissions Reduction Targets) (Scotland) Bill . The Bill proposes to extend Scotland’s 2050 greenhouse gas reduction target from 80% to 90%, and allows for a 100% (net-zero) target year to be specified in the future. It also makes amendments to the way that greenhouse gas emissions are calculated and reported on.
Alasdair Reid, Senior Researcher; Brexit, Environment and Rural Unit