Maritime climate
Maritime climate refers to the climate conditions that are moderated by proximity to the sea, typically characterized by mild temperatures and consistent rainfall throughout the year. This type of climate is commonly found in areas such as the coasts of Oregon and Washington in the United States, parts of New Zealand, Tasmania, and much of Western Europe. In a true maritime climate, winter daytime temperatures average around 15°C, while summer daytime temperatures can reach approximately 25°C. Rainfall averages about 10 centimeters per month, occurring without a distinct wet or dry season.
Though maritime climates are generally mild, they can experience extreme weather variations, with temperatures sometimes soaring above 35°C in summer or dropping below freezing in winter. While annual sunshine hours are typically ample, rainfall patterns can vary significantly, leading to both dry spells and intense rainfall events. As climate change progresses, true maritime climates may see increased temperatures and altered rainfall extremes, but they are generally resilient environments for both flora and fauna. New Zealand serves as a case study for understanding these climate impacts, particularly in the context of agricultural adaptation and development in regions previously dominated by different farming practices.
Subject Terms
Maritime climate
Definition
Maritime climates are generally considered to be those that are moderated by the sea. However, a true maritime climate is in most cases a climate in which it is neither very warm nor very cold, with adequate rainfall throughout most of the year. A typical maritime climate occurs on the coast of Oregon and Washington in the United States, in many parts of New Zealand, in Tasmania, and in much of Western Europe. Although surrounded by the sea, tropical islands are not normally considered to have a maritime climate but rather a tropical climate. True maritime climates usually have winter daytime temperatures of about 15° Celsius and winter nighttime temperatures of about 5° Celsius. In the summer, daytime temperatures average about 25° Celsius and nighttime temperatures average about 15° Celsius. Rainfall in a true maritime climate occurs throughout the year, with no pronounced wet or dry season, and averages 10 centimeters per month.
Despite the moderate nature of the true maritime climate, extremes do occur. In many maritime climates, daytime temperatures can reach above 35° Celsius, and occasionally even above 40° Celsius, while nighttime temperatures may reach 0° Celsius, and occasionally as low as –10° Celsius. Sunshine is generally more than adequate for plant growth, and annual bright sunshine hours of two thousand to twenty-five hundred hours are the norm. Rainfall, although generally adequate for plant growth, can vary: Maritime climates can have periods of up to six weeks without any appreciable rainfall, and there is at least one known instance of no rain at all falling during almost every month on the calendar. In contrast, monthly rainfalls of over 20 centimeters in a month are reasonably common, but monthly rainfalls of over 50 centimeters are not impossible. Although a daily rainfall of more than 0.3 centimeter is uncommon, at times, the rainfall in a twenty-four-hour period may exceed 20 centimeters. In summary, a true maritime climate is generally an easy climate to live in for people, plants, and animals, but relatively extreme events do occur.
Significance for Climate Change
Although the true maritime climate has milder winters, generally cooler summers, and greater temperature ranges from nighttime to daytime than do continental climates, there are many variations from place to place. For example, the climate of New York City, although situated on a coast, has a climate quite different from that of Vancouver, on the coast of British Columbia. Alterations in the true maritime climate brought about by are likely to be relatively small, and in most places plants and animals should be able to adapt to the change. However, if there is an overall increase in temperatures in the middle latitudes of both hemispheres, where most of the true maritime climates occur, summers are likely to become warmer, albeit not as warm as current continental climates, and winters are likely to have fewer days below freezing. Sunshine hours are unlikely to change, but rainfall extremes, especially on a daily basis, are likely to increase somewhat.
New Zealand is considered to have a typical maritime climate, although there are some areas in New Zealand that are quite dry, with an average annual rainfall of only 30 centimeters. Nevertheless, most of New Zealand, as well as much of Western Europe, has a typical maritime climate. New Zealand is an excellent case study as to the effects of global warming on the temperature and agricultural production of such a climate. Vineyards flourished in many parts of the country throughout the twenty-first century, but in the early 2000s, in the far south of New Zealand in the Southland district, there were no commercial vineyards. Instead, the district was a dairy country, covered with very green pastures and grazing cattle. However, the Southland District Council and the Southland Regional Council considered the probable effects on the region of changes predicted in the Intergovernmental Panel on Climate Change’s 2007 report and began to promote the prospects of the Southland district to become a major grape-growing region in the twenty-first century. By 2022, the region had grown to contain myriad wineries and vineyards. The wine-growing region of Central Otago in New Zealand, which lies at the 45th parallel, was the southernmost winery in the world at that time.
Bibliography
Capotondi, Antoinetta, et al. "A Global Overview of Marine Heatwaves in a Changing Climate." Communications Earth & Environment, 2024, doi.org/10.1038/s43247-024-01806-9. Accessed 20 Dec. 2024.
Oliver, John E. "Maritime Climate." Encyclopedia of World Climatology, 2005, DOI: 10.1007/1-4020-3266-8‗131. Accessed 20 Dec. 2024.
"The Ocean and Climate Change." NASA, science.nasa.gov/earth/explore/the-ocean-and-climate-change/. Accessed 20 Dec. 2024.