Video

After last week's morbid post that carried a dominating message of doom and gloom, I think it's time to move onto the theme of this blog and start to explore some of the ways in which we could solve this global issue.

In the place of the text-heavy posts of the previous weeks (and in hope of providing a joy similar to those rare school geography classes when the teacher wheels out the TV at the beginning of the lesson), I am instead going to recommend an insightful 12 minute video from the IPCC that provides a background on a few of the mitigation options that exist for a number of the major global sectors, some of which I will go explore in the coming weeks.

As is shown in the video, one of the most important factors in the success of climate change mitigation is the point at which effective action is taken. If measures are introduced immediately, the required reduction rate for emissions is half what it would be if there was no response until 2030. an important message from the video is that emission reduction needs to occur in all sectors and regions, and I will be investigating a number of these in the near future.

Do we need to intervene?

An often-heard argument from sceptics of anthropogenic climate change is that both the climate and atmospheric concentrations of carbon vary through the history of the Earth, and so who’s to say that the temperature changes that are occurring now are not a part of a natural climate cycle. It was even suggested to me, from an unnamed friend, that it is “incredibly ignorant” of humans to believe that they could influence a system as significant as our planet’s climate.

The Earth has seen vastly different climatic conditions through its 4.6 billion-year history, and on a range of timescales: tectonically-driven, 10⁵ to 10⁷ year processes; 10⁴ to 10⁶ year orbital cycles; and least commonly, abrupt changes that last anything from 1,000 years to 100,000 years (Zachos et al., 2001). These variations have involved differing temperatures and carbon dioxide concentrations, and if you go back around three million years, you’d be able to measure CO₂ levels as high as those found today.

So, if the climate is naturally variable, what evidence is there that humans have even contributed?

Signs of a human effect on atmospheric CO₂ exist from as far back as 7,000 years ago (Ruddiman, 2013). The latest interglacial, the Holocene, began around 12ka BP. At 7ka BP, a shift occurred which set the period apart from historical averages: the carbon dioxide and methane concentrations began to rise, contrasting the three previous interglacials in which CO₂ and CH₄ in the atmosphere gradually declined. Ruddiman shows this event matches with the onset of forest clearing and agricultural advances; such a seismic shift in the Earth’s behavioural pattern during similar interglacial periods as today must plant climate change concerns into the heartiest of sceptics.

This evidence, however, only scratches the surface of the anthropogenic influence on the atmosphere. Carbon dioxide concentrations - that had remained mostly constant not only through the last 1,000 years (Figure 1), but also through interglacial periods during the last 250,000 years - increased sharply following the Industrial Revolution (Figure 2). Fossil fuel energy production brought with it unfathomable population increases (current levels being seven-times the one billion alive in 1820) and a global economy 50-times greater than in 1800 (Steffen et al., 2007), both increasing the demand for energy even more: a domino effect on a planetary scale.

Figure 1 - CO2 through the last 1,000 years. (Ruddiman, 2013)

Figure 2 - CO2 concentrations during interglacial periods over the last 250,000 years. (Steffen et al., 2007) 

And, perhaps most concerning of all, is the unprecedented rate at which this increase in CO₂ has occurred: 75% of the CO₂ rise attributed to anthropogenic actions has been released since 1950 (Steffen et al., 2007), and this is predicted to have contributed 0.5-1.3^oC to the average global surface temperature (IPCC, 2014). In the ~250 years since 1750, the CO₂ concentrations measured in the atmosphere have sharply increased from a relatively-constant interglacial marker to levels not present on earth at any point in the last 800,000 years (Figure 3).

CO2 concentrations over the last 800,000 years (Source)

But what does this mean for the environment? Why do we need to cut our emissions?

As stated above, just the emissions since 1950 have caused an estimated 0.5-1.3^oC rise in global temperature. Steffen writes that there are three general scenarios that humankind could adopt in the future in regards to climate change:

(1)    Business-as-usual: Emissions continue to rise throughout the 21^st century.

(2)    Mitigation: A direct approach to tackle the problem, with the most extreme target being the return of the earth system to levels present before major human impact.

(3)    Geoengineering: A drastic form of mitigation, involving the intentional alteration of an earth system. An example is the pumping of aerosols into the atmosphere to reduce the amount of solar insolation reaching the earth surface.

The IPCC built upon these ideas in the Fifth Assessment Report (2014) with four Representative Concentration Pathways (RCPs), each presenting a different emission scenario based on the point at which anthropogenic release of CO₂ reaches its peak. Under RCP8.5, the ‘business as usual’ scenario in which emissions continue to increase throughout the 21^st century, global mean surface temperature is predicted to rise by a mean value of 3.7^oC, with the maximum of the forecasted range being as high as 4.8^oC (IPCC,2014). An inflation of temperatures such as this would have catastrophic consequences, most notably threats to human health, species survival and sea level rise (IPCC, 2014). A fantastic run-through of the different emission scenarios and their potential impacts is provided by Skeptical Science.

Introduction

In the time it will take you to read this post, approximately 200,000 tonnes of anthropogenic CO₂ will be released into the atmosphere (World Bank) – that’s nearly 1,500 blue whales worth of carbon dioxide. Although to most of us the exact nature of how global carbon emission reductions will be achieved remains a mystery, one thing is clear: collaborative effort is going to be key, with countries, communities and individuals needing to work alongside one another for the good of the planet.

Living just outside Brighton, and having spent three years as a resident of Bristol, I have been fortunate enough to experience two cities that are both substantially involved in fighting environmental issues. Brighton is host to the sole Green Party-held constituency in the UK, a telling summary of a city that is wildly known for its accepting views and passionate values; Bristol was named European Green Capital 2015 due to its longstanding pioneering for green schemes: Bristol has cycling rates three and half times the average for major UK cities.

Despite these cities, the UK as a whole appears to be slipping in its responsibilities for carbon reduction. The government have given permission for fracking to go-ahead in Lancashire, slashed renewable energy subsidies and become the only G7 country to increase their fossil fuel subsidies. Denmark, meanwhile, has pledged to reach 100% renewable energy in all sectors by 2050, and has a wind power network capable of powering its entire country with energy to spare.

Denmark's shift to fully renewable energy
Source: Greenpeace

 

COP21

Last December saw the 2015 United Nations Climate Change Conference take place in Paris. This was the 21st Conference of the Parties (hence its well-known, alternative title of COP21), an annual summit aimed at reviewing the global issue of climate change. Previous major outcomes of the meeting have included the Kyoto Protocol (COP3), the Montreal Action Plan (COP11), and the Green Climate Fund (COP17).

In the build up to the event, the conference was seen by many to be the most significant of all time. Its objective was principally simple but infinitely more problematic in reality: to draw up a legally binding plan to combat climate change, agreed to by all 195 member parties. 146 of the 195 countries submitted draft proposals before attending and, to the surprise of some (due to the calamitous shortcomings of COP15, where talks completely broke down and the US government was accused of espionage), an agreement was reached to limit warming of the planet to 2^oC, whilst “pursuing efforts” to limit the warming to 1.5^oC.

Perhaps unbelievably, given the vast complexity of the negotiations, reaching an agreed target was only a microscopic step towards the end goal. The intimidating task of actually reducing emissions to the level required for the 2^oC objective to be achieved now has to begin. The urgency of this is possibly best stated by the fact that global CO₂ levels have now passed 400ppm for almost certainly the final time in our lifetimes.

Global CO2 levels will not dip below 400 ppm again in our lifetimes.

Source: Guardian

Climitigation

This blog will focus on techniques to combat global warming and carbon emissions, including the triumphant (and less successful) methods of the past, the strategies currently in place, and those that may be implemented in the future in order to achieve the COP21 target. Climate change can be typified as fundamentally an environmental issue, though it obviously carries with it powerful social and economic ramifications, and so these will be touched on too, hopefully utilising some of my own experience in sustainability to review how different schemes could minimise the effect on local and global populations.

I’ll start next week with a brief breakdown of the wider picture and why climate change mitigation needs to be introduced. In the meantime, if you have any questions or comments then please submit them below!

Finally, here’s a nice little tool which summarises the potential warming from different emission scenarios.