Here are some answers to some of the most popular questions in week 4:
1) What is required in Paris this year to improve the effectiveness of mitigation measures?
There needs to a (long-overdue) global deal to reduce CO2 emissions. The countries that have historically emitted more should commit to reduce their emissions more, but no nation can be exempt from some action.
2) Clarification of the ‘global warming hiatus’ from 2000?
There has been a slow-down in the rate of warming suggesting that the ocean has been taking up heat faster than previously. Most of the excess energy coming into the planet goes into the ocean anyway, and there is natural variability in its heat storage. The extent of the hiatus varies somewhat between temperature reconstructions, because of a gap of weather stations e.g. in the Arctic which has been warming very fast. The slow-down may now be ending with 2014 being the warmest year on record in several reconstructions.
3) Would money be better spent focussing on developing renewable energy sources?
Money is being spent on encouraging the uptake of renewable energy technologies – for example, in the UK we have the feed-in tariff, which rewards people for installing solar photovoltaic cells on their houses. The signs are encouraging that global renewable energy capacity is starting to take off. I am looking forward to the ‘solar revolution’ – recent projections suggest that solar power (complemented by other renewable sources) will replace fossil fuels as the main global source of electricity during this century. With the right policy regime it will happen sooner rather than later.
4) Does solar radiation management interfere with the Earth’s magnetic field?
No, the Earth’s magnetic field is created by the flow of liquid iron in the Earth’s inner core. That’s one place that even the most ambitious would-be geoengineers can’t reach.
5) Why has the incorporation of Geo-engineering within IPCC scenarios not been more widely publicised?
This refers to the widespread use of biomass energy with carbon capture and storage (‘BECCS’) in the IPCC’s scenario to stay within 2C of global warming (called ‘RCP2.6’). It deserves to be widely known about, because currently governments are doing very little to invest in research and development for carbon dioxide removal technologies, whilst at the same time they are nominally signed up to the ‘2C target’. This is simply inconsistent.
6) Could a geoengineering ’solution’ help one country and harm another?
Yes. If there is unilateral deployment of sunlight reflection methods, for example the deliberate injection of aerosols into the stratosphere of one hemisphere and not the other this will have widespread repurcussions on other nations. See the discussion in this week’s feedback video for more on this.
More next week!