How are air pollution and agriculture related?

Transcription

1 How are air pollution and agriculture related? Frank Dentener European Commission, Joint Research Centre Co-chair Task Force Hemispheric Transport Air Pollution Sustainable food production and air pollution: reducing emissions generates many benefits Milan World Expo 2015.

2 Airpollution components and sources Road transport, industry and power generation are the best known sources of air pollution, producing particulate matter and ozone. Also agriculture is is contributing to air pollution emissions.

3 Air pollution a world wide problem Aerosol particles and nitrogen Impacts human health and biodiversity Ø In 2012 worldwide about 7 million people died prematurely from air pollution- especially in Asia- but in Europe also 400 thousand! Ø Ammonia emissions from London, middle of fertilizerxx century agriculturemanure and Ø Nitrogen emissions and deposition also have a negative impact biodiversity. Beijing, beginning of theon XXI century react with NOx from traffic to form ammonium nitrate particles. As other sources are increasingly controlled, agriculture becomes a more important source for airpollution 3

4 Tropospheric ozone Why do we worry about tropospheric ozone? NOx + CO VOC CH 4 Ø In ground-level air, ozone is a pollutant formed by sunlight-driven chemical reactions involving CO, VOC, NO x from vehicle exhausts, industry but also from CH 4 from agriculture Ozone is one the most harmful air pollutants: Ø Ozone is damaging agricultural crops and natural vegetation Ø Tropospheric ozone is an important climate gas warming the atmosphere. Ø Levels continue to exceed air quality thresholds to protect public health (EEA, 2015) Ø Peak ozone is going down, but mean ozone levels are not. 4

5 Global distribution and trends of tropospheric ozone Figure 1 Ozone trends Remote measurements of ozone in Europe, East Asia and Rest ofdistribution the world Global and trends of tropospheric ozone Surface ozone time series at several rural sites around the world. Trend lines are fit through the yearly average ozone values using the linear least-square regression method. Trend lines in Europe only extend through 2000 when the positive trend appears to have ended. This figure is modified from the original that appeared in IPCC (2013). doi: /journal.elementa f001 Figure 1 Surface ozone time series several rural sites around world. Trend lines are fit through yearly average ozone values u the linear least-square regress method. Trend lines in Eur only extend through 2000 w the positive trend appears to h ended. This figure is modi from the original that appeare IPCC (2013). Little America were driven by enhanced ozone values during the dark winter months. During summertime ozone at Little America was only 14 ppbv while ozone at Arkona was 30% greater (18 ppbv). Comparison of short-term ozone measurements at other coastal Antarctic sites to Arkona in the early and mid-1960s yields similar results (Oltmans and Komhyr, 1976). In the 1970s quantitative ozone measurements became more widespread and efforts were made to routinely doi: /journal.elementa monitor the atmosphere at rural and remote locations for the purposes of detecting long-term changes in the global composition of the atmosphere (Figure 1 and Table 1). Continuous records in southern Germany began at the rural hilltop site of Hohenpeissenberg in 1971 and the mountaintop site of Zugspitze (2670 m) in 1978 (Gilge et al., 2010), while continuous measurements began at the summit of Whiteface Mountain in upstate New York in 1973 (Oltmans et al., 2013). Ozone measurements at remote sites were established by the U.S. National Oceanic and Atmospheric Administration at its baseline observatories of Mauna Loa, Hawaii (1973), Barrow, Alaska (1973), the South Pole (1975), and American Samoa (1976) (Oltmans et al., 2013). Routine ozonesonde profiles became available in Germany, the US, Japan and Antarctica in the early 1970s (Oltmans et al., 2013), while ship-borne monitoring of the marine boundary layer of the North and South Atlantic Oceans began in the late 1970s (Lelieveld et al., 2004). Numerous long term ozone monitoring sites, measuring surface and free tropospheric ozone, were established in the 1980s and 1990s, with some of the most important rural or remote sites being Cape Grim, Tasmania (1982), Cape Point, South Africa (1983), Mace Head, Ireland (1987), Lassen Volcanic National Park, California (1987), Bermuda (1988) and Izaña, Canary Islands (1988). In addition, major regional ozone monitoring networks were established across Europe and North America. While there are many regions of the world still without ozone monitoring, the amount of data now available for ozone trend analysis is relatively extensive, and too cumbersome to briefly summarize with text or even with tables. In an attempt to easily and clearly relay information on ozone trends at multiple sites, Cooper et al. (2012) developed a map-based view of regional ozone trends across the United States. This approach was employed for summarizing global ozone trends in IPCC s Fifth Assessment Report (IPCC, 2013). While very useful for understanding Cooperglobal et al., 2014 ozone trends, the IPCC figures are tucked away in an electronic supplement and not highly visible (Hartmann et al., 2013). This review provides updated versions of the IPCC ozone trend plots, including recently published trends from South Korea, South Africa, Argentina, and two additional sites in Europe. Figure 2 shows all available ozone trends at the surface or within the lowermost troposphere (ozonesondes Ø Ozone increases in Europe prior to 1990 Ø Large increases in Asia and western America

6 What is HTAP? Ø Task Force on Hemispheric Transport of Air Pollution Ø Established in 2004 by the UNECE Convention on Long-Range Transport Air Pollution Ø Co-chaired by the European Commission and the U.S. EPA Ø An expert group of scientists across the world studying hemispheric transport of air pollution 6

7 Mandate of TF HTAP Ø Examine transport of air pollution across the Northern Hemisphere, including ozone (precursors) and PM and components (including black carbon), mercury, and persistent organic pollutants. Ø Assess potential emission mitigation options available inside and outside the UNECE region Ø Assess their impacts on regional and global air quality, public health, ecosystems, near-term climate change Ø Collaboration with other groups both inside and outside the Convention 7

8 Hemispheric transport Ø North America, Europe, South Asia and East Asia cover ca % of human-related emissions Ø Within one month the atmosphere in the Northern Hemisphere is mixed. Ø Ozone produced in Asia is transported to North America, from North America to Europe etc. NA EU EA SA Ø A special case is methane which stays about 10 years in the atmosphere, and is both a greenhouse gas and an air pollutant. Lower troposphere Mid-upper troposphere 8

9 Sciamachy Tropospheric NO 2 Air pollution Ø In North America and Europe NOx emissions have gone down with ca. 30 % in the last 2 decades. Ø but in Asia increasing by %!

10 Methane observations Ø Observations from a global network of CH 4 indicate continuous increases over the last two centuries Ø Small interruption but increasing again 10

11 Methane emission trends Fuel use and production Waste Agriculture Ø There are many sources of methane: agriculture (rice production, manure, cattle) contributes ca. 40 % of the man-made emissions Ø About half of the methane emissions comes from natural sources (not in figure), which may increase due to climate change. 11

12 Methane anthropogenic emissions Ø Agricultural regions in North and South America, Europe, South Asia, China Ø Fossil fuel production regions

13 HTAP attribution of O 3 changes in Europe NA EU EA SA Total O 3 change Within EU Outside of EU Methane Ø Annual average - large region global models Ø Largest O 3 (6 ppb) decreases before 1980; small reductions in O 3 during Ø O 3 reductions attributable to EU emissions compensated by increasing emissions elsewhere Ø Important contribution from CH % Ø Taken together changes in O 3 from outside Europe and CH 4 are larger than within EU (60-70 % of total) Ø External O 3 becomes more important when local sources are more regulated. Ø Hemispheric transport more important at lower concentrations 13 Wild et al, ACP, 2012

14 HTAP benchmark scenarios Policy Relevant Questions No Further Control (NFC) Current Legisla4on (CLE) NFC: What are the benefits of implemen4ng current policies in terms of health, ecosystems, and climate impacts? CLE: Given current policies, what are emissions likely to be in the future? GAINS Maximum Feasible Reduc4on (MFR) MFR: What technology and policy op4ons will be available (at a reasonable cost) to further mi4gate pollu4on problems in the future?

15 O 3 changes in Europe for HTAP global air pollution scenarios HTAP scenarios: Total O 3 change NFC No further control CLE Current Legislation MFR Maximum Feasible Reductions Within EU Outside of EU Methane For Europe: Ø Regional controls can still bring down ozone, but requires ambitious air pollution policy Ø Ambitious air pollution policy elsewhere may further help, especially in the US. Ø Methane emission reductions are going to be crucial for reducing ozone. Ø Methane is included in climate policies, but we will need to reduce it also for reducing ozone air pollution. Ø Reducing methane will require strong collaboration with countries in Asia 15 Wild, Klimont et al, 2015

16 Where are the benefits of reducing ozone? Wheat production loss due to ozone in 2000 Ø Year 2000 global economic losses estimated to cost $14-26 billion Ø Benefits of reducing ozone will be also in subtropical and tropical regions Van Dingenen et al,

17 Take home messages Ø The contribution of hemispheric O 3 to local pollution is increasing Ø Cooperation on a hemispheric or global scale to reduce tropospheric ozone, will facilitate achievement of local air quality objectives. Ø The Task Force Hemispheric Transport Air Pollution (TF HTAP) brings scientists together to inform policy on the role of hemispheric air pollution, their impacts, and mitigation options. Ø A portfolio of mitigation options is emerging- it is clear that emission reduction of CH 4 (producing O 3 ) is going to be very important- with important benefits from (and for) climate policies. Ø Reducing ozone will have large benefits for agriculture, and agriculture is also key to reducing methane and other air pollution emissions. Ø Global institutions (UNEP, FAO, UNECE, CCAC ) can help with raising awareness regarding options and benefit of reducing emissions, informing and facilitating international agreements. 17