CALS 500

A sad image of dead trees visible in the forest canopy

Drought on the “Wet” Coast

1 Comment / Academic Writing, CALS 500 /

Many British Columbians (BC) enjoyed the warm, extended summer this fall, but it was also strange for those of us on the west coast used to autumn rains filling the local streams. The extreme drought conditions overshadowed the warm days and, in some regions, lasted into November. Alyssa Charbonneau, a meteorologist with Environment and Climate Change Canada, reported that the length and severity of the drought, accompanied by unseasonably warm temperatures, was influenced by a high-pressure ridge persisting over the region (Romphf, 2022). The high-pressure ridge steered coastal rain storms up to Yukon and Alaska. As summer progressed into autumn, Level 4 drought became Level 5 drought. Level 5 drought is classified as exceptionally dry conditions and is almost sure to adversely impact society and the ecosystem (EmergencyInfoBC, 2022). This year’s drought, following last year’s extended Level 5 drought, has resulted in adverse impacts.

Some of the impacts that made the news are a state of emergency in three BC communities, salmon not able to spawn and dying when they tried, a failed wild mushroom harvest, trees and plants stressed or dying and a late-in-the-year increase in wildfires. BC Hydro also released a report about this year’s “driest and hottest extended periods on record” and the “near-record low water levels in river systems and some of BC Hydro’s smaller watersheds” (BC Hydro, 2022, p.1). This has included the watersheds with BC Hydro dams and generation on Vancouver Island, where I live. Figure 1 shows that for 23 of 52 streams monitored on Vancouver Island, the seven-day average streamflow percentiles were at drought Level 5. It is alarming for spawning salmon and the wildlife that rely on the salmon return, but it also raises concerns about electrical generation capacity at the dam sites. 

Are these negative impacts related to climate change?  Climate change is top of mind, considering the intensity and duration of the drought and the shift in the season. Fortunately, climate science can help us understand why these droughts and other unprecedented extreme climatic events are occurring with more frequency intensity and lasting longer.

Figure 1

Map of 7-Day Average Streamflow Vancouver Island – October 27, 2022

Note. This figure shows the 7-day average streamflow percentiles for streams monitored on Vancouver Island as of October 27, 2022. From British Columbia Drought Info, by Management Branch, Ministry of Forests, Government of B.C, 2022. https://governmentofbc.maps.arcgis.com/apps/MapSeries/index.html?appid=838d533d8062411c820eef50b08f7ebc. In the public domain.

 Climate science has found without a doubt that human-produced greenhouse gases accumulating in the atmosphere are causing rapid global warming (IPCC, 2021b, p.4). Also, warming and biodiversity loss are pushing the climate and planetary systems we depend on to their limit (Chen et al., 2021, p. 161). Recognizing this immense problem, world leaders signed the Paris Agreement in 2015. They agreed to keep the average global temperature rise by the end of the century well below 2oC above pre-industrial levels (1850-1900) and make efforts to keep warming to 1.5oC above pre-industrial levels (Chen et al., 2021, p. 150). Unfortunately, seven years later, the global average temperature is 1.09oC above pre-industrial levels and rising, with the expectation of hitting 1.5oC above pre-industrial before 2050 (Arias et al. 2021, p. 41 & 42). 

Therefore, there is an urgent need for action to reduce greenhouse gas emissions, and the critical messages from climate science that pertain to decision-makers, Canadians and those of us pondering the impacts of this latest Level 5 drought are:

  1. Every tonne matters – each additional tonne of CO₂ emissions adds to global warming (IPCC, 2021b, p. 28).
  2. Every fraction of a degree matters – each increment or fraction degree of global warming increases the intensity and frequency of extreme events (IPCC, 2021b, p.18).
  3. Extreme events will be unprecedented, even at 1.5oC of warming above pre-industrial levels (IPCC, 2021b, p.15).
  4. Multiple extreme events happen simultaneously as warming continues, especially heat waves and droughts (IPCC, 2021b, p.25).
  5. The rate of warming matters – the rate of warming increases the occurrence of extreme events (Fischer et al., 2021, p. 692), such as heat waves and droughts.

In summary, as greenhouse gas emissions increase, warming increases, which can cause multiple extreme events, such as heat waves and drought, to happen simultaneously. The faster the warming, the more record-shattering the event. In British Columbia, we are acutely aware that these events are not far off in the future but have already happened. Without substantive emissions reductions, we can expect frequent and extreme drought, heatwaves and wildfire season.

The challenge of our lifetime is to reduce our reliance on oil and gas, the primary source of human-caused greenhouse gas emissions (Arias et al., 2021, p.80). As Island Health Medical Health Officer Dr. Shannon Waters advises, “[t]he gravity of this situation necessitates a fundamental shift: We must place the well-being of our environment at the centre of all our decision-making” (Public Health Agency of Canada, 2022, p. 29). Stopping warming before reaching 2oC above pre-industrial levels is critical to avoid a climate with such hot extremes that a healthy life is not supported (Arias, 2021, p. 120). In addition, deep emissions cuts now would limit the rate of warming and exposure to unprecedented extreme events. In the meantime, until the climate is stabilized, we must also adapt and prepare for the changing climate. 

To that end, the province of British Columbia completed a preliminary risk assessment in 2019. At that time, they assessed the impact of a Level 4 drought as high when it “affect[ed] two or more regions of the province and last[ed] two or more months” (BC Risk, 2019, p.40). The report noted that such a scenario could be considered extreme, with 2015 being a recent example. Unfortunately, that extreme was exceeded in 2021, with thirteen regions in BC reaching Level 4 drought for up to three months and four regions reaching Level 5 drought for up to two months (Management Branch, Ministry of Forest, 2022).

Figure 2

Drought Map of British Columbia as of October 27, 2022

Note: The brown areas represent the regions at Level 5 Drought and the red areas at Level 4. The areas comprising Vancouver Island and the lower mainland of BC (southwest portion of the map) showing Level 5 and 4 droughts are historically known for rain and a wet environment. From British Columbia Drought Info, by Management Branch, Ministry of Forests, Government of B.C, 2022. https://governmentofbc.maps.arcgis.com/apps/MapSeries/index.html?appid=838d533d8062411c820eef50b08f7ebc

The summer and fall of 2022 have also been exceptionally dry. As shown on the map in Figure 2 for 2022, the drought was not as long as 2021, but ten regions were in Level 5 drought for a month or more. This is unprecedented, extreme, and gravely concerning for communities whose watersheds are affected. To help communities adapt, the province of BC is funding a watershed security initiative that will work with Indigenous Peoples and various levels of government to collaborate on building healthy watersheds well into the future (B.C. Gov. News, 2022). In addition, the world, including BC, must grapple with its forestry practices that have decimated watersheds and impacted hydrological cycles, causing drought and flooding (Douville et al., 2021, p. 1057). Intact old-growth trees are an essential part of the hydrological cycle for the “wet” coast watersheds and must be retained and expanded (Wood, 2021, p.22). Thus, as the rains arrive, thoughts of drought cannot wash away. British Columbians must prepare for the next time, possibly as soon as next year.

Only a trickle of water at the water fall
Millstone River waterfall is a mere trickle rather than full and gushing with autumn rain and spawning salmon.

 

 

References

Arias, P.A., N. Bellouin, E. Coppola, R.G. Jones, G. Krinner, J. Marotzke, V. Naik, M.D. Palmer, G.-K. Plattner, J. Rogelj, M. Rojas, J. Sillmann, T. Storelvmo, P.W. Thorne, B. Trewin, K. Achuta Rao, B. Adhikary, R.P. Allan, K. Armour, . . . K. Zickfeld, (2021). Technical Summary. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 33−144, https://doi:10.1017/978100915789

BC Gov News (2022, January 25). B.C. is securing watersheds for a stronger future. Government of B. C. https://news.gov.bc.ca/releases/2022ENV0007-000103

BC Hydro. (2022, October). Casting drought: How climate change is contributing to uncertain weather and how BC Hydro’s generation system is adapting. https://www.bchydro.com/content/dam/BCHydro/customer-portal/documents/news-and-features/bchydro-report-casting-drought.pdf

Chen, D., M. Rojas, B.H. Samset, K. Cobb, A. Diongue Niang, P. Edwards, S. Emori, S.H. Faria, E. Hawkins, P. Hope, P. Huybrechts, M. Meinshausen, S.K. Mustafa, G.-K. Plattner, and A.-M. Tréguier. (2021). Framing, Context, and Methods. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L., Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R., Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 147–286, doi:10.1017/9781009157896.003.

Climate Institute (n.d.). The Biosphere. Retrieved October 26, 2022, from https://climate.org/canlifechangetheearth/

Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, and O.  Zolina. (2021). Water Cycle Changes. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I  to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1055–1210, https://doi:10.1017/9781009157896.010

EmergencyInfoBC. (2022, October 20). Severe Drought: Multiple Communities in B.C. October 14, 2022. Government of B.C. https://www.emergencyinfobc.gov.bc.ca/severe-drought/

Fischer, E. M., Sippel, S., & Knutti, R. (2021). Increasing probability of record-shattering climate extremes. Nature Climate Change, 11(8), Article 8. https://doi.org/10.1038/s41558-021-01092-9

IPCC. (2021a). Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256. doi:10.1017/9781009157896.022  

IPCC. (2021b). Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 3−32, https://doi:10.1017/9781009157896.001

Kimmerer, R.W. (2013). Braiding Sweetgrass. Milkweed Editions. https://milkweed.org/book/braiding-sweetgrass

Management Branch, Ministry of Forests. (2022). British Columbia Drought Info. Government of B.C. Retrieved October 27, 2022, from https://governmentofbc.maps.arcgis.com/apps/MapSeries/index.html?appid=838d533d8062411c820eef50b08f7ebc 

Public Health Agency of Canada. (2022). Chief Public Health Officer of Canada’s Report on the State of Public Health in Canada 2022: Mobilizing Public Health Action on Climate Change in Canada. Ottawa, ON: Public Health Agency of Canada. https://www.canada.ca/content/dam/phac-aspc/documents/corporate/publications/chief-public-health-officer-reports-state-public-health-canada/state-public-health-canada-2022/report-rapport/report.pdf

Romphf, J. (2022, October 20). ‘Big shift’ to rainy, cool fall weather headed for Vancouver Island after drought. Comox Valley Record. https://www.comoxvalleyrecord.com/news/big-shift-to-rainy-cool-fall-weather-headed-for-vancouver-island-after-drought/

Seneviratne, S.I., X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, F. Otto, I. Pinto, M. Satoh, S.M. Vicente-Serrano, M. Wehner, and B. Zhou. (2021). Weather and Climate Extreme Events in a Changing Climate. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1513–1766, doi:10.1017/9781009157896.013.

Wood, P. (2021). Intact Forests, Safe Communities Reducing community climate risks through forest protection and a paradigm shift in forest management. Sierra Club BC. https://sierraclub.bc.ca/wp-content/uploads/2021-Forest-Climate-Risk-Assessment-Report-final-February.pdf

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Drought

Leave a Comment / CALS 500 /

When I started reading IPCC reports, I became aware of the various type of droughts. The following is a brief description of the types. Also, a graphic showing the climate drivers of drought and a table showing the primary impacts from the different drought categories.

Drought

The primary contributing factor to drought is the lack of precipitation over a long enough period to cause severe hydrological impacts. See the Figure below for the climate drivers involved.

Graphic showing climatic drivers of drought

From: Douville et al., 2021

Meteorological drought

A persistent lack of precipitation over a long enough period causes a meteorological drought (Douville et al., 2021).

Hydrological drought

As the drought persists over time, water supply within soil, streams, lakes and reservoirs decreases(Douville et al., 2021). These can be widespread and affect many eco and social functions, as shown in Table 1 (Loon, 2015).

Agricultural drought

Agricultural drought occurs when soil moisture, due to a lack of precipitation and high atmospheric evaporation demand, becomes so abnormally low that the growing season and crop production are negatively affected (IPCC, 2021 & Douville et al., 2021).

Ecological drought

Like agricultural drought, abnormally low soil moisture affects land or terrestrial ecosystems, including forests (IPCC, 2021). Insufficient moisture in the total soil water column affects tree roots and their ability to transport water and impedes the carbon cycle, weakening and ultimately killing the tree (Seneviratne et al., 2021). The structure of the soil can be damaged as well.

Flash drought

Typically, droughts take time to develop; however, a flash drought can unexpectedly and rapidly evolve (Douville et al., 2021).

Megadrought

Megadrought is a drought that occurs over many years (Douville et al., 2021).

A table listing the major impacts of the different type of drought

From: Van Loon, 2015.

References

Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, and O.  Zolina. (2021). Water Cycle Changes. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I  to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1055–1210, https://doi:10.1017/9781009157896.010.

IPCC. (2021). Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. MassonDelmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, https://doi:10.1017/9781009157896.022.

Seneviratne, S.I., X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, F.  Otto, I.  Pinto, M. Satoh, S.M. Vicente-Serrano, M. Wehner, and B. Zhou. (2021). Weather and Climate Extreme Events in a Changing Climate. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I  to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R.  Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1513–1766, https://doi:10.1017/9781009157896.013.

Van Loon, A.F., (2015, July/August). Hydrological drought explained. WIREs Water 2015, 2:359–392. doi: 10.1002/wat2.1085

 

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