Month: January 2015

With climate models, simpler isn’t necessarily better

Grantham Institute Co-Director Professor Joanna Haigh discusses a recent paper which argues that  existing climate models ‘run hot’ and overstate the extent of manmade climate change.

Retro filtered picture of smoky chimneys silhouettes against sunIt is perplexing that some climate change sceptics, who expend much energy in decrying global circulation (computer) models of the climate, on the basis that they cannot properly represent the entire complexities of the climate system and/or that they contain too many approximations, are now resorting to an extremely simplified model to support their arguments.

The model used in the Sci. Bull. article is a very useful tool for conceptualising the factors which contribute to the relationship between increasing concentrations of carbon dioxide in the atmosphere and global average temperature – indeed, we use such models as teaching aids for students studying atmospheric physics – but it is in no way fit for purpose as an accurate predictor of climate change.  It requires as input the values of a number of parameters and, fundamentally, the choice of these values determines the predicted temperatures

Key here is the “feedback parameter” which represents the knock-on effects of changes in the atmosphere on the initial response to greenhouse gas warming.  A positive feedback will make the temperature change larger and a negative one reduce it.  For example, as the atmosphere warms it can hold more water vapour which itself is a greenhouse gas, acting to enhance the initial carbon dioxide-induced warming and thus giving a positive feedback.  The physics of this process is very well-understood.  There are a number of other, both positive and negative, feedback processes but overall, analyses of meteorological observations, modelling and understanding of the physical processes point to a significantly positive value.  In the present paper the authors choose a very small value, based on temperatures measured in ice cores over the 810,000 year period of ice ages and inter-glacials.  Their analysis is incomplete but anyway not relevant to changes in global climate over decadal-to-century timescales.

Thus by choosing an inappropriate value of the feedback parameter, and also judicious choices of other parameters, the authors end up with their “models run hot” conclusion.  Must try harder.

Internship Experiences: Skidmore, Owings & Merrill

The Climate and Environment at Imperial blog has moved. View this post on our new blog

by Peter Blair, Science and Solutions for a Changing Planet DTP student

Thames-Basin
The Thames Basin, a Map Highlighting Urban Areas

The Thames Basin is set to face many challenges in the future: climate change, a growing population and economic requirements all present developmental challenges, as well as major sources of uncertainty. Having previously worked on a voluntary project producing a vision for planning in the Great Lakes Basin over the next hundred years, Skidmore Owings and Merrill (SOM) were interested in applying the same methodology to the Thames Basin to determine how we may best plan for the future in this area.

During the summer of 2014, prior to starting the NERC Science and Solutions for a Changing Planet Doctoral Training Partnership at Imperial College, I undertook the exciting opportunity of an internship with Skidmore, Owings and Merrill, looking at the future of planning of development in the Thames Basin.

Who are SOM?

SOM, short for Skidmore, Owings and Merrill, are a world-leading firm of architects, structural engineers and urban planners. They have designed buildings such as the Burj Khalifa and the Broadgate Tower (where their London office is now based), and have worked on the Imperial College Campus master plan, amongst many other projects.

What did I do?

I used SOM’s Great Lakes investigation as an inspiration for looking at planning in the Thames Basin, identifying the assets that the basin has, for example extensive infrastructure, a thriving economy, a history of innovation and a rare depth of culture, the issues that it faces, including overcoming archaic governance boundaries, managing water in the face of both drought and flood, and coping with the change and uncertainty that climate change brings. I produced a booklet identifying first ideas for a vision of what planning in the Thames Basin could be built around in the future. Elements of this vision include integrating the various planning documents that exist into a more cohesive, basin-level plan, recognition of the positive feedback cycles that exist between ‘green’ and ‘blue’ policies and using infrastructure to develop a holistically connected basin.

What did I gain?

I had a fantastic time at SOM: I met a lot of great people with amazing ideas and skills, and was also able to develop myself while there. The internship gave me the freedom and time to develop new skills that are hugely useful, but which I would probably not have had the opportunity to investigate otherwise. One example would be ArcGIS, which allows for the creative display of map-based data, and which I will be able to utilise as part of my PhD, but which I may never otherwise have had to opportunity to learn. I was also able to ‘dip my toe’ into the corporate environment, without having to jump straight in. This showed me the different emphasis which is placed on various aspects of work in business compared to academia: the importance of delivering a positivist message and looking at the big picture, distilling a great amount of information into a short message and using images to convey meaning.

What did SOM gain?

Hopefully SOM feel as though they have gained from my undertaking of this internship as well. As I was a short-term member of the team, SOM were able to work on a different kind of project that was perhaps less corporate and which required different skills. While many other members of the team were working on multiple projects at any one time, I was also able to give my focussed attention to the Thames Basin project. This internship has also strengthened the link between SOM and Imperial College, and building links with academia is something that SOM have been very keen to do.

 

Find out more about Peter’s PhD project

2014 – the warmest year on record

Thermometer2A summary of global temperature for 2014 from NASA and NOAA has just been published, showing that the average global temperature for 2014 was 0.69°C above the average for the 20th century. The small margin of uncertainty in calculating average global temperature means that the exact ranking of 2014 cannot be distinguished from the previous record years of 2005 and 2010, but it is nominally the warmest year on record. The ten warmest years have all occurred since 1998.

Professor Jo Haigh, Co-Director of the Grantham Institute, commented on the report saying that: “This and other indicators are all pointing in the same direction of continued global warming, reflecting the overall upward trend in average global temperatures”

A large amount of warming was seen in the oceans with globally-averaged sea surface temperature 0.57°C above the 20th century average. This is consistent with recent studies that have suggested that much of the extra energy in the Earth system is going in to the oceans. You can read more about the significance of ocean heat uptake in our blog post.

An update from the Met Office on global temperatures is expected later this month and we look forward to seeing the further detail that this will add.

See the full report on the NOAA website.

Who’s responsible for tackling climate change? – COP 20 outcomes

Smog in guangzhou1000
Smog in Guangzhou, China

By Dr Flora Whitmarsh, Grantham Institute

An agreement produced by the 20th Conference of the Parties in Lima, Peru, noted ‘with grave concern’ that countries’ current pledges on emissions reductions are insufficient to keep global temperature rise within either 2°C or 1.5°C of pre-industrial levels. This is indeed a serious concern because temperature changes of just a few degrees are enough to change the climate significantly. Rising sea levels, melting mountain glaciers and polar ice caps and increases in extreme precipitation have already been observed. These trends will continue with ongoing greenhouse gas emissions, and it is expected that we will continue to see an increase in extreme high sea levels, an increase in the intensity of the heaviest rain, and changes in the global distribution of rainfall.

The Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have until March 2015 to provide updated emissions pledges. The 1994 UNFCCC protocol aims to achieve the ‘stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system’. The protocol made it clear that countries have ‘common but differentiated responsibilities and respective capabilities’, implying that developed nations who are responsible for historical emissions should make the deepest cuts. An agreement drafted during COP 20 added the phrase ‘in light of different national circumstances’. The new deal to some extent blurs the distinction that has existed between developed and developing nations. However, it remains to be seen exactly how the responsibility to reduce emissions will be spread between different countries.

China’s per capita emissions are now at EU levels, but when total cumulative emissions of greenhouse gases are taken into account – carbon dioxide is long lived in the atmosphere so the total emissions over time are what matter – the five countries most responsible for global warming on a per capita basis are the United Kingdom, the United States, Canada, Russia and Germany. When countries are ranked by their absolute contribution to global warming so far, the top five are the United States, China, Russia, Brazil and India, and the United Kingdom is number seven on the list. Of course, the reason for the United Kingdom’s high ranking on both these lists because it industrialised early. Different studies disagree on the exact ranking, but on a per capita basis the developed nations bear most of the responsibility for the temperature increases we have already seen. Nevertheless, there is increasingly a need for the richer developing nations to take some action as well.

The coming months are a critical time for the global climate change negotiations. There have already been encouraging signs: the United Kingdom and the EU have led the way with ambitious pledges, and China and the United States have taken a positive step forward with their recent bilateral agreement. However, more needs to be done. It is right that the United Kingdom and the EU are leading the way on this, but it is also vital that the political will remains to tackle climate change as we move into a crucial stage of the negotiations. Action is urgently needed – in order to avoid temperatures rising more than 2°C above pre-industrial levels, global emissions should peak by 2020. Delaying the peak in emissions until 2030 will increase the costs of taking action and make it very difficult to keep to this target. Meeting the 2°C target will require the leaders of the developed world to continue to increase the level of ambition over the coming months.