Inside Science >> When a 2°C rise isn't a 2°C rise

18th April 2011

Related Topics

Related tags

  • Mitigation



Limiting global temperature increases to below plus 2°C compared with the pre-industrial average is a long-standing goal for international climate-change mitigation efforts.

A change in global average temperatures of plus 2°C above pre-industrial levels does not sound dramatic to most people. It is misguided , however, as changes in global average annual temperatures can mean much larger changes regionally, with greater extremes.

The UK summer heatwave in 2003 led to more than 2,000 premature deaths in the UK, with the highest ever recorded maximum temperature of 38.5°C occurring in Faversham; the average summer temperature increase across the UK was just plus 2°C.

Research by the Met Office shows that for a 2°C global rise, the hottest day in a UK summer could increase by up to 8°C. In general, a global average of 2°C warming comprises greater than average warming over land and lower than average over oceans, but there is much local variation.

The Intergovernmental Panel on Climate Change in its fourth assessment report (released in 2007) suggested that 20%–30% of species could ultimately face extinction with temperature increases of 1.5–2.5°C.

One of the striking things about the report was the shift in linking significant impacts to relatively smaller degrees of average temperature change compared with earlier assessments.

In other words, as more evidence of climate impacts accumulates, it is becoming increasingly clear that a 2°C warming raises significant issues in a number of areas, and the assessment of “dangerous” levels of change has been shifted downwards, towards lower temperature increases.

In polar regions, for example, a global average temperature rise of 2°C could result in temperature increases of as much as 6°C, which includes feedback where the normal “albedo effect” – ice reflecting much incoming solar radiation – is reduced due to ice melt.

There are large uncertainties over the amount of sea level rise that may occur as a result of melting ice caps in Antarctica and Greenland. Different studies suggest ranges of sea level rise between 0.5–2 metres by 2100 if temperatures rise by less than 2°C.

Given the current lack of sufficient commitments globally to reduce greenhouse-gas emissions at the required rate to have even a 50% chance of limiting warming to no more than 2°C, much research effort now is focused on the risks and consequences of warmer scenarios, and the challenges in adapting to these.


Subscribe to IEMA's newsletters to receive timely articles, expert opinions, event announcements, and much more, directly in your inbox.

Transform articles

EU and UK citizens fear net-zero delivery deficit

Support for net zero remains high across the UK and the EU, but the majority of citizens don't believe that major emitters and governments will reach their climate targets in time.

16th May 2024

Read more

There is strong support for renewable energy as a source of economic growth among UK voters, particularly among those intending to switch their support for a political party.

16th May 2024

Read more

Taxing the extraction of fossil fuels in the world’s most advanced economies could raise $720bn (£575bn) by 2030 to support vulnerable countries facing climate damages, analysis has found.

2nd May 2024

Read more

The largest-ever research initiative of its kind has been launched this week to establish a benchmark for the private sector’s contribution to the UK’s 2050 net-zero target.

2nd May 2024

Read more

Weather-related damage to homes and businesses saw insurance claims hit a record high in the UK last year following a succession of storms.

18th April 2024

Read more

The Scottish government has today conceded that its goal to reduce carbon emissions by 75% by 2030 is now “out of reach” following analysis by the Climate Change Committee (CCC).

18th April 2024

Read more

The Science Based Targets initiative (SBTi) has issued a statement clarifying that no changes have been made to its stance on offsetting scope 3 emissions following a backlash.

16th April 2024

Read more

While there is no silver bullet for tackling climate change and social injustice, there is one controversial solution: the abolition of the super-rich. Chris Seekings explains more

4th April 2024

Read more

Media enquires

Looking for an expert to speak at an event or comment on an item in the news?

Find an expert

IEMA Cookie Notice

Clicking the ‘Accept all’ button means you are accepting analytics and third-party cookies. Our website uses necessary cookies which are required in order to make our website work. In addition to these, we use analytics and third-party cookies to optimise site functionality and give you the best possible experience. To control which cookies are set, click ‘Settings’. To learn more about cookies, how we use them on our website and how to change your cookie settings please view our cookie policy.

Manage cookie settings

Our use of cookies

You can learn more detailed information in our cookie policy.

Some cookies are essential, but non-essential cookies help us to improve the experience on our site by providing insights into how the site is being used. To maintain privacy management, this relies on cookie identifiers. Resetting or deleting your browser cookies will reset these preferences.

Essential cookies

These are cookies that are required for the operation of our website. They include, for example, cookies that enable you to log into secure areas of our website.

Analytics cookies

These cookies allow us to recognise and count the number of visitors to our website and to see how visitors move around our website when they are using it. This helps us to improve the way our website works.

Advertising cookies

These cookies allow us to tailor advertising to you based on your interests. If you do not accept these cookies, you will still see adverts, but these will be more generic.

Save and close