Six things you didn't know about climate change

Published on: 23 March 2015

Reducing carbon emissions is vital to achieving climate targets. Image courtesy of Shutterstock.

Climate change is seen globally as a major environmental risk and has been a hot topic of discussion in the media for many years. But what about those things that aren’t talked about in the mainstream media?

To mark Word Meteorological Day (March 23) we have asked some of our world-leading researchers to tell us some things we didn’t already know about climate change.

1. Warmer winters will not decrease the number of winter deaths

It is widely assumed that harmful health effects associated with cold periods in northern Europe will be partially offset as climate change leads to milder winter weather, and recent UK government reports suggest that the expected higher temperatures in winter will result in fewer deaths. However, over the past few decades the UK and other temperate countries have simultaneously introduced better housing, improved health care, and ensured greater awareness of the risks of cold. This has caused the link between low winter temperatures, illness and death to weaken.

Researchers at the University of Exeter Medical School have shown that the association of year-to-year variation in winter deaths with the number of cold days in winter (less than five degrees centigrade), was evident until the mid-1970s, but then disappeared. This leaves just the incidence of flu-like illnesses to explain year-to-year variations in winter death rates.

Although weather-related winter deaths do still occur, the severity of cold winters is no longer a major predictor of the illnesses and deaths that will occur in England and Wales. Instead, the effectiveness of vaccination programmes, improvements in living conditions and better education are of greater importance.

Professor Michael Depledge, Chair in Environment and Human Health

2. A warmer climate could alter the number of males and females of some species

In many wildlife species the environment in which they live, as well as their underlying genetics, strongly influences whether individuals become males or females. Species with temperature-dependent sex determination may be especially susceptible to climate change. 

Warmer temperatures during embryonic development have been shown to induce female-biased populations in many reptiles, including tortoises, turtles and crocodiles. Conversely, in lizards, fish and some amphibians, temperature elevation during early life tends to induce male development. Male-biased sex ratios may be far more problematic for wildlife populations, as females determine the size of populations. 

Other environmental stressors predicted to accompany climate change (reduced nutrition, overcrowding, inbreeding and, in aquatic environments, increasing chemical residues, acidification and reduced dissolved oxygen) may also generate male-skewed sex ratios, and some of these stressors have been shown to have additive effects.

Professor Charles Tyler, Professor of Environmental Biology and Ross Brown, Postgraduate Researcher

3. The same computer models are used for weather and climate predictions

The same computer models of the Earth system are used for weather prediction and for climate change projections. These models simulate the dynamics and thermodynamics of the atmosphere, oceans, land surface, and ice, by solving a complex system of equations.

But the relative importance of different processes changes in the two cases. For instance, for weather forecasting, slow changes in the ocean circulation have little effect, so the ocean component can be `switched off', whereas they are crucial for climate change.

On the other hand, weather forecasting is done at the highest resolution affordable to capture fine details of weather systems, whereas climate projections are done at coarser resolution in order to run the model for tens or hundreds of simulated years.

Unifying weather and climate models in this way greatly accelerates efforts to improve the models: thus, improvements designed to increase the accuracy of weather forecasting often also improve the ability to simulate climate, and vice versa.

Professor John Thuburn, Met Office Joint Chair in Geophysical Fluid Dynamics

4. Global warming can be disrupted by natural climate fluctuations

An increase in greenhouse gases in the atmosphere causes the global mean temperature to rise, but this rise is not expected to result in a smooth upward trend in temperature. The observed record of global mean temperature shows periods of rise over a decade or so that are more rapid than the general trend and periods where the trend is less rapid.

In the last 10-15 years, the global mean temperature trend has been relatively flat and this period has been called the ‘pause’ or ‘hiatus’ in warming. This has happened despite a continued rise in greenhouse gases in the atmosphere. So, what can cause such fluctuations?

The short answer is, we do not fully understand. There are some candidate factors such as relatively small eruptions of volcanoes produce small particles that can block out sunlight and cause cooling plus the amount of energy the climate system receives from the sun can also vary. However a more likely explanation involves storage of heat in the ocean.

The last decade or so has seen a period when the east-to-west blowing Trade Winds in the Pacific Ocean have been relatively strong. This has led to colder than average sea temperatures at the surface in the eastern Tropical Pacific, and an accumulation of warm water below the surface in the western tropical Pacific. The cold eastern Pacific has a global influence, rather like that which occurs during the cold phase of El Nino. Quite why the Trade Winds have been strong is still a bit of a mystery - but is an active topic of research.

Professor Mat Collins, Joint Met Office Chair in Climate Change

5. To achieve climate targets we must dramatically reduce carbon emissions from energy

Energy is an area where technologies and approaches are already available that if deployed at scale would deliver major reductions in emissions. Compared to other sectors, such as heavy industry, there are arguably greater possibilities for achieving high rewards in terms of emission reductions. This means we should be preparing for some quite significant changes to our energy system, including how we use energy and how it is supplied.

Major proposals include, moving our heating systems away from gas boilers to a combination of district heating systems and heat pumps; increasing the numbers of, and eventually moving to, hybrid and electric cars and vehicles; and significantly reducing the amount of electricity that comes from fossil fuels by increasing levels of renewable energy technologies, such as solar, and nuclear energy. 

Public opinion research on these changes shows high favourability toward renewable energy systems even when the implications for cost increases are presented, but also indicates a need for greater government support to generate the proposed changes in transport and heat.  

Dr Catherine Butler, Advanced Research Fellow in Environment and Sustainability

6. People respond to images of flooding in the same way they do to images of wind turbines

A team of researchers led by Dr Saffron O'Neill have found that people respond to climate change images in the same way: there is, what has been termed, a 'consistent visual discourse' about climate change. For example, this work showed that most people will feel a similar way about an image of flooding (that it makes climate change seem important, but distant and scary, and that they are unable to do anything about it) and about an image of a wind turbine (that it doesn't make climate change seem important, but that it does make people feel empowered to act on climate change). So if we're concerned about engaging people with the climate challenge, then image matters!

Dr Saffron O'Neill, Senior Lecturer in Human Geography

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