Climate Change and its Adverse Effects

Earth’s climate has been constantly changing.
From 1901 to 2012 there was a warming trend in almost every corner of the world, which was caused mainly by human activities. The earth’s climate used to be affected primarily by natural hazard such as solar activity, changes in the earth’s orbit and volcanic activity. However, since the First Industrial Revolution in 1760, which resulted in an increasing concentration of greenhouse gases in the atmosphere, human factors have gradually overshadowed natural ones to become the main contributor to climate change. Climate change, in turn, has become the most significant challenge for humans at present and in the future.

According to data, the global surface temperature warmed by 0.85°C on average between 1880 and 2012, and each of the last three decades was warmer than the previous one. Statistics also show that the period from 1983 to 2012 was likely the warmest 30-year period of the past 1,400 years in the Northern Hemisphere. Global warming has become an indisputable fact. What effects have this change had on mankind? First of all, sea levels are rising due to the thermal expansion of seawater and a combination of glaciers, ice caps as well as ice sheets in Greenland and Antarctica melting into oceans, all of which is related to global warming. Since 1992, the massive loss of the Greenland ice sheet has accelerated. The average ice loss increased from 34 billion tonnes per year over the period 1992-2001 to 215 billion tonnes per year over the period 2002-2011. The average ice sheet loss in Antarctica increased from 30 billion tonnes per year over the period 1992-2001 to 147 billion tonnes per year over the period 2002-2011. The ice sheet that was lost mainly came from the northern Antarctica Peninsula and the Amundsen Sea sector of western Antarctica.

The same is true for glaciers. Changes in the length, area, volume and mass of glaciers show that global glaciers have almost all continued to shrink, with an average loss of 226 billion tonnes per year between 1971 and 2009, and 275 billion tonnes per year between 1993 and 2009. During the period 1979-2012, the average extent of Arctic sea ice decreased by approximately 3.5% - 4.1% per decade, i.e., 0.45 to 0.51 million sq km per decade, and the minimum extent of summer sea ice decreased by approximately 9.4% - 13.6% per decade, i.e., 0.73 to 1.07 million sq km per decade. The shrinking of the Arctic summer sea ice in the past three decades has been unprecedented in the past 1,450 years. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the global average sea level rose at a rate of about 1.7 mm per year between 1901 and 2010, and accelerated to approximately 3.2 mm per year between 1993 and 2010. Since the mid-19th century, the earth’s sea level has risen at a rate higher than the average rate over the past two millennia.

A changing climate leads to changes in the frequency, intensity, duration, spatial extent and timing of extreme weather events. According to the IPCC’s Fifth Assessment Report, there has been a decrease in the number of cold days and nights and an increase in the number of warm days and nights on a global scale since 1950. Since the mid-20th century, there has been one heat wave after another. The 2010 Russian heat wave killed more than 10,000 people in Moscow. The average temperature in Moscow in July that year was 7.6°C higher than normal, the city's hottest July on record. Climate change also contributes to droughts. Since the 1950s, some regions of the world have experienced a trend towards more intense and longer droughts, in particular in southern Europe and West Africa. But in some regions, droughts have become less frequent, less intense, or shorter, for example, in central North America and north-western Australia. There is evidence that human activities changed the distribution of drought-affected areas in the second half of the 20th century. In early August of 2012, droughts extended to the US. More than half of the states in the US were declared disaster areas, 90% of which were affected by droughts. Abrupt food price increases, triggered by droughts in the US and Eastern Europe, led to the World Bank’s Food Price Watch report at the end of August of the same year.

The magnitude and rate of climate change have also caused rapid and irreversible regional changes in the composition, structure and function of terrestrial and freshwater (including wetland) ecosystems. Mid-low to high greenhouse gas concentrations have led to increasing deterioration due to ocean acidification, posing a huge threat to marine ecosystems, especially polar ecosystems and coral reefs. In many places, melting ice and snow affect hydrological systems, which in turn affect water resources. Climate change is projected to reduce renewable surface water and groundwater resources significantly in most dry subtropical regions, and to keep degrading water quality in the 21st century. Research has found that climate change also has a significant negative impact on crop yields. For example, if the local temperature rises by 2°C from the end of the 20th century, and no appropriate measures are taken, the overall output of major crops, such as wheat, rice, and corn, in most tropical and temperate regions will decrease, putting global food supply in jeopardy.

Climate warming has also resulted in more deaths related to hot weather. For example, more local people died due to more and more intense heat waves or fires, such as the California wildfires in 2018 which caused over 100 fatalities. People in poor areas are more likely to suffer from malnutrition due to reduced crop yields. The risk of spreading diseases through food and water is also on the rise. Climate change is projected to worsen the health of people in many areas in the 21st century, especially in low-income developing countries. Climate change affects not only human beings but also the delicate balance of ecosystems. Many terrestrial, freshwater, and marine species have long changed their geographic distribution, seasonal activities, migration patterns, numbers and interactions with other species due to climate change. For species that fail to adapt to climate change quickly, the number will decrease or such species may even become extinct. Global warming has also brought more and stronger typhoons, threatening human properties and lives. Research shows that the number of tropical cyclones and very strong tropical cyclones in the Atlantic Ocean has increased significantly since the 1970s. Given the foregoing, it is, therefore important to provide accurate weather forecasting to reduce the risk of adverse impact from severe weather on human lives and livelihoods, such as farming. Indeed, the Hong Kong Observatory (HKO) and several other tropical cyclone warning centres have compiled best track data sets for tropical cyclones in the Northwest Pacific in order to predict the trend of the number of tropical cyclones more accurately.

Hong Kong Observatory – Helping to Raise Awareness of Climate Change

The "MyObservatory" is a weather app for smartphones recently developed by the HKO, providing personalised weather services for users. The app provides current weather data, including temperature, relative humidity, rainfall, wind direction and speed, as well as weather photographs collected from nearby weather stations at users’ locations, specified locations, or selected weather stations. Weather photos and rainfall data are updated at 5 and 15-minute intervals respectively, and other data at a 10-minute interval. When thunderstorms affect some regions of Hong Kong and the HKO issues a thunderstorm warning that mentions the affected regions, the thunderstorm warning icon on the main page of the app is marked with a red dot. Upon clicking the icon, a map is displayed to enable easy viewing of the regions affected by the thunderstorm warning. Rainfall and lightning forecasts in users’ or designated locations can also be provided based on artificial intelligence technologies, and the trial "Dr Tin" Chatbot Service provides a convenient and interactive means for users to enquire about weather information. The "MyObservatory" mobile app developed by the HKO came first in the "Public weather forecasts and information - information content" category and earned an honourable mention in the "Specialised apps award - weather warnings" category at the World Meteorological Organisation (WMO) International Weather Apps Awards 2020 (WIWAA). The WMO is a specialised agency of the United Nations focusing on weather and climate. The WMO WIWAA was organised for the first time this year to recognise well-designed mobile applications for providing reliable weather and climate information. The competition received more than 110 entries from all over the world. The "MyObservatory" app has been downloaded more than 8 million times, which is quite impressive.

In addition to the "MyObservatory" mobile app, the "Observatory Open Day 2021" hosted by the HKO with the theme "The Ocean, Our Climate and Weather" has been live-streamed on the Observatory’s Facebook page to draw public attention to climate change. Moreover, in response to ever more frequent extreme weather events such as extreme high temperatures and rainfall due to global warming, causing serious damage and even casualties to different parts of the world, the "2016-2020 Top Ten Mind-boggling Weather and Climate Events Selection" was organised by the HKO in 2021. The results of the online voting whereby citizens could select online five weather and climate events from the shortlist in each of the Hong Kong and Worldwide categories, were announced on the Open Day of the HKO.

In the Hong Kong category, the event with the most votes, i.e., 4,731 votes, was "Super Typhoon Mangkhut slammed Hong Kong with record-breaking storm surge." On 16 September 2018, Super Typhoon Mangkhut hit Hong Kong head-on, causing the most serious damage to Hong Kong since Super Typhoon Ellen in 1983. Typhoon Mangkhut necessitated the issuance of the Hurricane Signal No 10 for ten hours and brought violent winds and the worst storm surge on record. The sea level in Victoria Harbour rose to 3.88 metres above Chart Datum, the highest since typhoon Wanda struck Hong Kong in 1962. Mangkhut left many coastal and low-lying areas in Hong Kong severely flooded, resulting in at least 458 reported injuries and hundreds of ships being stranded, sunk or severely damaged. There were more than 60,000 reports of fallen trees and the power supply interruption affecting 40,000 households.

The second-placed event, with 3,552 votes, was "Intense cold surge brought freezing weather to Hong Kong". In late January of 2016, a severe cold snap hit Hong Kong causing freezing temperatures. The lowest temperature recorded at the HKO was 3.1°C on 24 January 2016, the coldest day in nearly 60 years. It even fell to -6°C on Tai Mo Shan. Extensive frost, fog and icy weather occurred in parts of the New Territories and highlands, accompanied by freezing rain and ice particles.

In the third place was "Super Typhoon Hato hit Hong Kong", which received 3,430 votes. Super Typhoon Hato struck Hong Kong head-on on 23 August 2017, and the HKO issued Hurricane Signal No 10 for five hours. The storm surge generally raised the water level in Hong Kong by about one to two metres, which combined with the high astronomical tide, caused the sea level in Victoria Harbour to rise to 3.57 metres above Chart Datum. Many low-lying areas in Hong Kong, Kowloon and the New Territories were flooded by sea water. At least 129 people were injured and there were more than 5,300 reports of fallen trees during the passage of Hato through Hong Kong. In addition, there were five tropical cyclones in 2017. The HKO had to issue tropical cyclone warning signals No 8 or above, tying with the records for 1964 and 1999.

The fourth place was taken by "The first-ever black rainstorm warning in October", with 2,869 votes. On 19 October 2016, under the combined effect of tropical cyclone Sarika and the northeast monsoon, Hong Kong was hit by a severe rainstorm, triggering the first Black Rainstorm Warning signal issued by the HKO in October. The October rainfall recorded that year was six times higher than normal, and the rainfall throughout the autumn (from September to November) reached a record-breaking 1,000 mm.

In the fifth place, with 2,724 votes, was "2020: Record-breaking numbers of very hot days and hot nights". There were 47 very hot days and 50 hot nights in Hong Kong in 2020, and 21 hot nights in a single month (July), all ranking among the highest on record. Hong Kong also experienced the hottest summer on record (June-August) in 2020, with July becoming the hottest month in Hong Kong since 1884.

In the Worldwide category, "Destructive wildfires ravaged Australia and California" ranked first with 4,242 votes. From 2019 to 2020, wildfires occurred in many areas of Australia and in California in the US as high temperatures and droughts intensified, causing major disasters. Starting from September 2019, wildfires occurred in many places in Australia, which were gradually brought under control by March 2020. It was estimated that 21% of Australia’s forested area had been burnt and more than one billion animals had died. In 2020, nearly 10,000 wildfires occurred in California in the US, burning more than 17,000 sq km of land.

"Greenland lost a record amount of ice in 2019" took the second place with 3,705 votes. Greenland lost a record amount of 532 billion tonnes of ice in 2019, equivalent to a million tonnes per minute, or 400 Olympic-sized swimming pools of ice every minute on average.

"Temperature in a Siberian town soared to 38 degrees in 2020" ranked the third with 3,022 votes. The Siberian town of Verkhoyansk, located in the Arctic Circle, was hit by a heat wave on 20 June 2020. It recorded a temperature of 38°C, the highest on record in the Arctic Circle.

In the fourth place, "Widespread drought in Africa caused severe food shortage" received 2,851 votes. In early 2016, many countries in southern Africa experienced severe droughts and crop losses. According to the World Food Programme, an estimated 18.2 million people needed emergency assistance.

And in the fifth place, "The five-year average of 2016-2020 is the warmest on record" received 2,752 votes. The five years from 2016 to 2020 were the warmest five-year period since records began in 1850. For more information about notable weather and climate events, please visit the website of the HKO.

Global Annual Summit

Through the voting activity, the HKO has successfully aroused public interest in significant weather and climate events in Hong Kong and around the world in the past five years, and also raised public awareness of extreme weather and climate change and their effect on the ecological environment. More importantly, global climate change is a matter of concern for the international community. A summit bringing together 197 Heads of State from around the world will discuss climate change as well as the response plans, commitments and actions of various countries.

The global annual climate summit (Conference of the Parties or COP) refers to an annual summit where 197 Heads of State discuss climate change and each country’s response plans, commitments and actions. The summit is part of the United Nations Framework Convention on Climate Change (UNFCCC), signed by almost all countries and regions in the world, with the main aim of controlling and limiting the impact of human activities on the climate. The Convention entered into force on 21 March 1994. COP26, the 26th summit to be held since 1994, is scheduled to be hosted by Scotland’s largest city of Glasgow from 1 to 12 November 2021.

In addition to discussing countermeasures, the upcoming summit will also provide an opportunity for leaders of all countries to review and evaluate the progress made so far since the signing of the 2015 Paris Climate Agreement, and to summarise the lessons of failure. This agreement, also known as the Paris Agreement, is fundamentally a strategic plan drawn up by mankind to avoid climate disasters. The plan is based on a major premise: if global warming continues and the temperature rises to 1.5°C above pre-industrial levels, many irreversible and catastrophic changes will occur on the earth.

In order to ensure that the terms of the agreement are effectively complied with and all commitments are faithfully implemented, it is required that countries meet once a year to report on the progress of the work and discuss specific issues such as their respective action strategies, progress, obstacles, difficulties and small goals.

At COP21 in Paris, some key aspects with the aim of preventing any catastrophic climate change were set out before the end of the summit. The Heads of State pledged to reduce greenhouse gas emissions, increase the production of renewable energy, keep a global temperature rise well below 2°C and pursue efforts to limit the temperature increase even further to 1.5°C, as well as invest billions of US dollars in helping poor countries combat the impact of climate change. In addition, the countries participating in the Paris summit reached consensus on conducting progress assessments, reviewing achievements, identifying problems, and determining next steps every five years. As one of the important items on the agenda of the COP26 Glasgow summit, the Paris Agreement signed five years ago will be assessed. Its results will have a critical impact on the international community and the destiny of mankind and deserve everyone’s attention. But before then, let us all make our own contribution to mitigate climate change by reducing our carbon footprints!

Hong Kong Observatory
BBC News

May 2021