UNIPCC report - Global Warming of 1.5C

The United Nations’ Intergovernmental Panel on Climate Change (1) recently produced a special report on the impacts from a 1.5 degree C increase in global temperature. The report details analyses and modelling that suggest the impacts from a temperature increase of 1.5 C are generally less severe than would occur at 2.0 C. This finding probably won’t come as a too much of a surprise to US policy makers so the perhaps the accompanying discussion into likely regional excursions from the global average and details into key impacts are designed to provide policy makers with specific examples they can use to drive policy action.

Many will want to look beyond the examples of warming induced impacts and seek guidance on actions needed to achieve decarbonisation. The report provides this through four different, theoretical emission reduction pathways. The detail behind each pathway highlights the different levers nations will need to use as they implement schemes to decarbonise their economies. Some of these levers, particularly those associated with the electricity sector, will be very familiar to elected US officials – in all four pathways there is a significant increase in generation from renewables and a major decrease in fossil fuel usage, especially for coal.

The US has been steadily reducing coal usage since 2007. Thermal coal consumption is down 40 % over the past 10 years with natural gas, wind and solar making up the shortfall. The IPCC report effectively states that this trend must be continued. The current US wind and solar generation fleet, which produced about 10% of US electricity in 2017, needs to be replicated at least every 5 to 6 years through 2050 with a strong likelihood that significant battery or equivalent storage capability is added in the back half of this period.

The recent boom in US gas production has been the biggest contributor to reduced reliance on coal. Unless a new generation of gas plants fitted with Carbon Capture and Sequestration (CCS) is built, this will only be a temporary phenomenon as conventional gas generation will need to be phased out en route to decarbonisation.

As challenging as this level of renewable expansion, together with a major roll out of utility scale storage and/or CCS, maybe be – think NEPA approvals, financing, local land use opposition – the IPCC report highlights a risk that the US climate debate is too renewable centric. US policy makers and those attempting to influence climate action should take careful note that while all of the emission reduction pathways presented have a significantly expanded renewable fleet none relies solely on renewables for decarbonisation.

In addition to a transformation of the power sector, cuts in the order of 50% to emissions from gas usage outside the power sector and also from gasoline and petroleum derivatives are also needed.

The agriculture sector also potentially has an important role to play – through reduced livestock methane emissions, afforestation activities and through widespread production of fast growing bioenergy crops.

Bioenergy with Carbon Capture and Sequestration (BECCS) will be considered by some as the option of last resort – it is the major negative emission technology presented in the IPCC report and hence is relied upon under scenarios in which prior emission actions have been avoided or delayed. BECCS involves growing biofuels specifically for power generation (thereby replacing coal and gas) with the resulting CO2 captured and geologically stored. This results in “negative” emissions because the biofuel crop takes CO2 out of the atmosphere as it grows and then after combustion to generate electricity the resulting CO2 is permanently sequestered underground removing it from the carbon cycle.

So what should be the key lessons for the US?

Reduced demand through greater efficiency and behaviour change work in all scenarios. High energy prices will drive down demand but policy makers may want to look for more innovative ways to reward low energy lifestyles

Decarbonising the transportation sector will need cheap, reliable electric vehicles to avoid actions like restricting personal vehicle usage

Ensuring a low emissions power sector might require an expanded nuclear fleet.

CCS is presented an important technology option. The IPCC report uses it in combination with bioenergy crops for carbon removal but only grudgingly with gas and not at all with coal. Perhaps all technologies that produce low and zero emissions electricity need to be considered as potentially viable options. As a minimum the criticality of CCS needs to be recognised.

If the thought of a massive US based BECCS rollout involving the conversion of most of the mid west corn belt to some sort of switch grass is too crazy to contemplate then perhaps that is the point the authors were trying to make.

The phrase “all of the above” was once a common cliché in energy debate – an objective reading of the IPCC special report suggests it is still valid.