Analysis: Global CO2 Emissions Set to Rise 2% in 2017 After Three-Year ‘Plateau’
By Zeke Hausfather
Over the past three years, global CO2 emissions from fossil fuels have remained relatively flat. However, early estimates from the Global Carbon Project (GCP) using preliminary data suggest that this is likely to change in 2017 with global emissions set to grow by around two percent, albeit with some uncertainties.
Hopes that global emissions had peaked during the past three years were likely premature. However, GCP researchers say that global emissions are unlikely to return to the high growth rates seen during the 2000s. They argue that it is more likely that emissions over the next few years will plateau or only grow slightly, as countries implement their commitments under the Paris agreement.
2017 emissions likely to increase
The GCP is a group of international researchers who assess both sources and sinks of carbon. It has published an annual global carbon budget report since 2006. Its newly released global carbon budget for 2017 provides estimates of emissions by country, global emissions from land-use changes, atmospheric accumulation of CO2, and absorption of carbon from the atmosphere by the land and oceans.
The figure below shows global CO2 emissions from fossil fuels, divided into emissions from China (red shading), India (yellow), the U.S. (bright blue), EU (dark blue) and the remainder of the world (grey). After a rapid increase in global emissions of around three percent per year between 2000 and 2013, emissions only grew by 0.4 percent per year between 2013 and 2016.
Annual CO2 emissions from fossil fuels by major country and rest of world from 1959-2017, in gigatons CO2 per year (GtCO2). Note that 2017 numbers are preliminary estimates. Data from the Global Carbon Project and available here. Chart by Carbon Brief using Highcharts.
Much of the slowdown in the growth of global emissions in recent years has been driven by a combination of reductions in the U.S. and China, as well as relatively little growth in emissions in other countries. This changed in 2017, with little-to-no reductions in U.S. emissions and a sizable increase in Chinese emissions.
India's emissions increased a bit more slowly in 2017 than in the past few years, while the EU's emissions have remained relatively flat since 2014 and did not noticeably change in 2017. The growth in emissions from 2016 to 2017 also more than doubled in the rest of the world.
The total emissions for each year between 2014 and 2017 and the countries that were responsible for the change in emissions are shown in the figure below. Annual emissions for 2014, 2015, 2016 and estimates for 2017 are shown by the black bars. The colored bars show the change in emissions between each set of years, broken down by country. Negative values show reductions in emissions, while positive values reflect emission increases.
Annual global CO2 emissions from fossil fuels (black bars) and drivers of changes between years by country (colored bars). Negative values indicate reductions in emissions. Data from the Global Carbon Project. Chart by Carbon Brief using Highcharts.
As 2017 is not yet over—and somewhat limited data is available—these projections are still subject to large uncertainties. The global estimate of a two percent increase in emissions could be as low as 0.8 percent or as high as three percent, the researchers said. The GCP will publish more complete 2017 numbers in early 2018 when all the data is available.
The GCP reported that China's emissions are projected to grow by 3.5 percent in 2017, with wide uncertainty ranging from 0.7 percent to 5.4 percent. China represents the single most important reason for the resumption of global emissions growth in 2017. This is driven by a projected three percent increase in coal consumption, 12 percent increase in natural gas consumption and five percent increase in oil consumption.
While the past few years have seen similar increases in natural gas and oil consumption in China, 2017 will reverse a few years of flat or declining coal consumption. The GCP reports that the 2017 increase in coal consumption—and, in turn, overall Chinese emissions—is driven by a combination in increased industrial production and reduced hydroelectric generation associated with lower-than-usual rainfall.
However, industrial growth has started to slow down again over the past three months, which might signal slower emissions growth and coal consumption in 2018.
The best estimate of 2017 U.S. emissions is for a decline of about 0.4 percent, though they could decrease by as much as 2.7 percent or increase by as much as 1.9 percent. This will likely be a smaller decrease than in past years, as U.S. emissions have declined by around 1.2 percent per year over the past decade. This reflects a modest uptick in coal use for electricity generation in the U.S. and an associated decline in gas use. 2017 will likely be the first time in the past five years that U.S. coal consumption has risen.
India's emissions are projected to grow by two percent in 2017 (ranging from 0.2 percent to 3.8 percent), lower than, on average, the six percent growth in emissions over the past decade. This appears to be mostly due to reduced oil consumption growth and a six percent reduction in cement production. Coal consumption increased at a similar rate to prior years.
Global carbon budget
Every year the GCP provides an estimate of the global carbon budget, which estimates both the release and uptake of carbon including emissions from fossil fuels and industry, emissions from land-use changes, carbon taken up by the oceans and land, and changes in atmospheric concentrations of CO2. This differs from the commonly used term "carbon budget," referring to how much emissions are left to meet a climate target, such as avoiding 2°C warming.
The most recent budget, including estimated values for 2017, is shown in the figure below. Values above zero represent sources of CO2—from fossil fuels and land use—while values below zero represent sinks of CO2, where the sources of CO2 end up. CO2 emissions either accumulate in the atmosphere, or are absorbed by the oceans or land vegetation.
Annual global carbon budget of sources and sinks from 1959-2017. Note that the budget does not fully balance every year due to remaining uncertainties, particularly in sinks. Note that 2017 numbers are preliminary estimates. Data from the Global Carbon Project and available here. Chart by Carbon Brief using Highcharts.
Land-use changes, such as deforestation and fires, comprised 11 percent of total emissions in 2017, marginally down from the 13 percent average over the past decade. The remaining 89 percent of emissions came from fossil fuels and industry. Total CO2 emissions decreased by about two percent between 2015 and 2016, driven entirely by lower land-use emissions.
In 2017, overall CO2 emissions—including land use—are likely to increase by around 1.5 percent, as land-use emissions are estimated to remain roughly the same as in 2016. This means that total CO2 emissions are likely to be similar as in 2015, with the increase in fossil fuel emissions being offset by the decrease in land-use emissions.
About 54 percent of CO2 emitted in 2016 accumulated in the atmosphere, while the remainder was taken up by carbon sinks—24 percent by the land and 22 percent by the ocean. The portion of CO2 accumulating in the atmosphere in both 2015 and 2016 was higher than average, driven in part by the large El Niño event. This is expected to drop to around 46 percent in 2017, as it is a year lacking a major El Niño.
Updating sources and sinks
The GCP's new global carbon budget also includes updated estimates of sources and sinks based on changes in inventories and new research published since the last budget came out. The figure below, taken from the paper presenting the latest budget, shows the budget values used for every year from 2006 through to present.
Global Carbon Project source and sink estimates in gigatons carbon (GtC)—note, not CO2—for every Global Carbon Budget published between 2016 and 2017. Figure 9 from Le Quéré et al (2017).
Estimates of fossil fuel emissions were revised downwards a bit from the 2016 report, particularly between 1990 and 2010. This was due largely to a change in the dataset used to estimate Chinese emissions.
The GCP's new global carbon budget also incorporates updated land-use emission estimates that significantly revise past land-use change emissions, showing higher emissions prior to 1960, lower emissions between 1960 and 1999, and higher emissions from 1999 through to present. This ends up changing estimates of cumulative carbon emissions since the pre-industrial period, but given the large uncertainties involved the authors caution against using these revisions to draw conclusions about remaining carbon budgets associated with staying within the 2°C or 1.5°C warming targets.
Implications for limiting warming to 2°C
As previously discussed by Carbon Brief, the later that global emissions peak, the more rapid the reductions must be to limit warming to 2°C. The figure below shows how the rate of reduction varies based on peak year, adding in the new estimated 2017 emissions.
Emission reduction trajectories associated with a 66 percent chance of avoiding more than 2°C warming by starting year, with new 2017 emissions added. Solid black line shows historical emissions, while dashed black line shows emissions constant at 2016 levels. Data and chart design from Robbie Andrew at CICERO and the Global Carbon Project. Chart by Carbon Brief using Highcharts.
The increase in emissions in 2017 makes it more challenging for the world to limit warming to "well below 2°C", as per the Paris agreement—at least in the absence of large-scale removal of carbon dioxide from the atmosphere from as-yet-unproven negative emission technologies later in the century.
While the slowdown in emissions over the past few years and the "peaking" of emissions by a number of countries has been cause for cautious hope, this is tempered by the uptick in emissions projected in 2017. According to UN Environment, existing commitments by nations fall well short of what is needed to meet warming targets and emissions will not fall quickly until the world undertakes much more ambitious mitigation actions.
Reposted with permission from our media associate Carbon Brief.
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Kevin T. Smiley
When hurricanes and other extreme storms unleash downpours like Tropical Storm Beta has been doing in the South, the floodwater doesn't always stay within the government's flood risk zones.
New research suggests that nearly twice as many properties are at risk from a 100-year flood today than the Federal Emergency Management Agency's flood maps indicate.
Flooding Outside the Zones<p>About <a href="https://furmancenter.org/files/Floodplain_PopulationBrief_12DEC2017.pdf" target="_blank">15 million</a> Americans live in FEMA's current 100-year flood zones. The designation warns them that their properties face a 1% risk of flooding in any given year. They must obtain flood insurance if they want a federally ensured loan – insurance that helps them recover from flooding.</p><p>In Greater Houston, however, <a href="https://doi.org/10.1111/j.1539-6924.2012.01840.x" target="_blank">47% of claims</a> made to FEMA across three decades before Hurricane Harvey were outside of the 100-year flood zones. Harris County, recognizing that FEMA flood maps don't capture the full risk, now <a href="https://www.hcfcd.org/floodinsurance" target="_blank" rel="noopener noreferrer">recommends that every household</a> in Houston and the rest of the county have flood insurance.</p><p>New risk models point to a similar conclusion: Flood risk in these areas outstrips expectations in the current FEMA flood maps.</p><p>One of those models, from the <a href="https://firststreet.org/flood-lab/research/2020-national-flood-risk-assessment-highlights/" target="_blank">First Street Foundation</a>, estimates that the number of properties at risk in a 100-year storm is 1.7 times higher than the FEMA maps suggest. Other <a href="https://doi.org/10.1088/1748-9326/aaac65" target="_blank" rel="noopener noreferrer">researchers</a> find an even higher margin, with 2.6 to 3.1 times more people exposed to serious flooding in a 100-year storm than FEMA estimates.</p>
What FEMA’s Flood Maps Miss<p>Understanding why areas outside the 100-year flood zones are flooding more often than the FEMA maps suggest involves larger social and environmental issues. Three reasons stand out.</p><p>First, some places rely on relatively old FEMA maps that don't account for recent urbanization.</p><p>Urbanization matters because impervious surfaces – think pavement and buildings – are not effective sponges like natural landscapes can be. Moreover, the process for updating floodplain maps is locally variable and can take years to complete. Famously, New York City was updating its maps when Hurricane Sandy hit in 2012 but hadn't finished, meaning flood maps in effect <a href="https://projects.propublica.org/nyc-flood/" target="_blank">were from 1983</a>. FEMA is required to assess whether updates are needed every five years, but the <a href="https://www.fema.gov/cis/nation.html" target="_blank" rel="noopener noreferrer">majority of maps</a> <a href="https://www.oig.dhs.gov/sites/default/files/assets/2017/OIG-17-110-Sep17.pdf" target="_blank" rel="noopener noreferrer">are older</a>.</p><p>Second, binary thinking can lead people to an underaccounting of risk, and that can mean communities fail to take steps that could protect a neighborhood from flooding. The logic goes: if I'm not in the 100-year floodplain, then I'm not at risk. Risk perception <a href="https://doi.org/10.1088/1748-9326/ab195a" target="_blank" rel="noopener noreferrer">research</a> backs this up. FEMA-delineated flood zones are the major factor shaping flood mitigation behaviors.</p><p>Third, the era of climate change scuttles conventional assumptions.</p><p>As the planet warms, extreme storms are becoming <a href="https://nca2018.globalchange.gov/" target="_blank">more common and severe</a>. If greenhouse gas emissions continue to increase at a high rate, computer models suggest that the chances of a severe storm dropping 20 inches of rain on Texas in any given year will increase from about 1% at the end of the last century to 18% at the end of this one, a chance of <a href="https://doi.org/10.1073/pnas.1716222114" target="_blank" rel="noopener noreferrer">once every 5.5 years</a>. So far, <a href="https://www.rstreet.org/wp-content/uploads/2020/02/195.pdf" target="_blank" rel="noopener noreferrer">FEMA hasn't taken into account the impact climate change is having</a> on extreme weather and sea level rise.</p>
Racial Disparities in Flooding Outside the Zones<p>So, who is at risk?</p><p>Years of research and evidence from storms have highlighted social inequalities in areas with a high risk of flooding. But most local governments have less understanding of the social and demographic composition of communities that experience flood impacts outside of flood zones.</p><p>In analyzing the damage from Hurricane Harvey in the Houston area, I found that <a href="https://doi.org/10.1088/1748-9326/aba0fe" target="_blank">Black and Hispanic residents disproportionately experienced flooding</a> in areas beyond FEMA's 100-year flood zones.</p><p>With the majority of flooding from Hurricane Harvey occurring outside of 100-year flood zones, this meant that the overall impact of Harvey was racially unequal too.</p><p>Research into where flooding occurs in Baltimore, Chicago and Phoenix points to some of the potential causes. <a href="https://www.nap.edu/read/25381/chapter/4#16" target="_blank" rel="noopener noreferrer">In Baltimore and Chicago</a>, for example, aging storm and sewer infrastructure, poor construction and insufficient efforts to mitigate flooding are part of the flooding problem in some predominantly Black neighborhoods.</p>
What Can Be Done About It<p>Better accounting for those three reasons could substantively improve risk assessments and help cities prioritize infrastructure improvements and flood mitigation projects in these at-risk neighborhoods.</p><p>For example, First Street Foundation's risk maps account for <a href="https://firststreet.org/flood-lab/research/flood-model-methodology_overview/" target="_blank">climate change</a> and present <a href="https://floodfactor.com/" target="_blank" rel="noopener noreferrer">ratings</a> on a scale from 1 to 10. FEMA, which works with communities to update flood maps, is <a href="https://www.fema.gov/media-library-data/1521054297905-ca85d066dddb84c975b165db653c9049/TMAC_2017_Annual_Report_Final508(v8)_03-12-2018.pdf" target="_blank" rel="noopener noreferrer">exploring rating systems</a>. And the National Academies of Sciences, Engineering and Medicine recently <a href="https://www.nationalacademies.org/news/2019/03/new-report-calls-for-different-approaches-to-predict-and-understand-urban-flooding" target="_blank" rel="noopener noreferrer">called for a new generation of flood maps</a> that takes climate change into account.</p><p>Including recent urbanization in those assessments will matter too, especially in fast-growing cities like Houston, where <a href="https://authors.elsevier.com/a/1boBRyDvMFW6W" target="_blank" rel="noopener noreferrer">386 new square miles</a> of impervious surfaces were created in the last 20 years. That's greater than the land area of New York City. New construction in one area can also <a href="https://scalawagmagazine.org/2018/01/city-in-a-swamp-as-houston-booms-its-flood-problems-are-only-getting-worse/" target="_blank" rel="noopener noreferrer">impact older neighborhoods downhill</a> during a flood, as some Houston communities discovered in Hurricane Harvey.</p><p>Improving risk assessments is needed not just to better prepare communities for major flood events, but also to prevent racial inequalities – in housing and beyond – from <a href="https://www.npr.org/2019/03/05/688786177/how-federal-disaster-money-favors-the-rich" target="_blank" rel="noopener noreferrer">growing</a> after the unequal impacts of disasters.</p>
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