Climate zones are a categorization of the world’s regional climates based on weather patterns. One of the most widely used systems for identifying climate zones is the Köppen-Geiger climate classification system. It delineates climate zones by using a combination of monthly average temperature and precipitation that make up the typical weather patterns in a place.
Life in every climate zone has adapted to the stable local weather patterns of the past 12 thousand years: This is true of plants and animals, but also humans, our built environment, and the systems that keep our societies running. As our planet warms due to human greenhouse gas emissions, local weather patterns are changing in each climate zone. The changes brought on by rising temperatures are so significant that some places could transition into completely different climates.
Certain transitions from one climate to another have greater implications for local life than others, such as the change from a wet climate zone to a dry one. Lebanon, bordering the Mediterranean Sea to the West and desert to the East, has had a temperate climate for thousands of years. Temperate climate zones are important to the world’s population—the vast majority of humans today live in temperate climates, where temperatures are comfortable and agriculture is productive. As the planet warms, many places are becoming consistently hotter and drier. Around Lebanon, desert and arid land is expanding, pushing up against the historic local climate zone.
Lebanon at 0.5°C of warming
Climate zone: primarily temperate, dry summer, hot summer
Population: 5.5 million (2020)
Risk factors: drought, heat, wildfire
Lebanon is a narrow, coastal nation in the Middle East, bordering the Mediterranean Sea to the West with 140 miles (225 km) of coastline. It is part of a region composed of coastal plains, mountains, and valleys, known for its fertile soil, and home to some of the earliest settled civilizations.
Historically, most of Lebanon experienced a temperate climate, characterized by mild weather, cool and rainy winters, and warm dry summers. Thanks to this climate, Lebanon was a lush, hospitable stretch of mostly fertile land, with sea to the West that buffered its climate against hot desert and dry, arid land to the East.
For thousands of years, Lebanon has been an exceptional sliver of lush land with a favorable climate surrounded by neighboring desert. As global average temperatures continue to rise, the arid regions to the East are expanding.
Lebanon at 1°C and beyond
Between 1971 and 2000, Earth’s global average temperature was 0.5°C above the pre-industrial average. More recently, we’ve moved past 1°C, so we use 1°C of warming as a proxy for the weather that we’re used to—the recent past. At 1°C, Lebanon was still mostly in its historic climate zone: temperate, dry summer, hot summer (dark blue in the map key). However, the half-degree increase in global temperature led to subtle shifts in climate within Lebanon’s borders.
With 1°C of warming, Lebanon became hotter. Most grid cells that previously showed temperate, dry summer, warm summer climate (teal in the map key) transitioned to having dry hot summers (dark blue). In fact, at 1°C of warming, only one of these teal grid cells with a warm summer remained.
The rainy winters that defined Lebanon’s climate also changed. At 0.5°C of warming, Lebanon contained just one grid cell with a semi-arid climate (brown in the map key), found in the north. By 1°C, a neighboring grid cell transitioned from a temperate and rainy climate to a dry, semi-arid climate (from blue to brown). This is the first sign that the land within Lebanon’s borders may become permanently dry—a process called aridification.
Around Lebanon from 0.5°C to 1°C, we see the dry, hot, arid desert to the East of Lebanon, represented by light brown grid cells, expand west into the buffer of slightly less dry and hot climates represented by darker brown and tan cells. The land surrounding Lebanon is steadily becoming hotter and drier.
The next warming threshold, 1.5°C, is impending (and the closest to the climate in 2024). 2°C of warming is a potential future scenario. At 1.5°C, Lebanon no longer has any teal grid cells containing a temperate, warm-summer climate. Summers in Lebanon are now hot. In the region around Lebanon, those light brown dry, hot, arid desert cells continue to expand, eating into the darker brown buffer zones.
At 2°C, an additional grid cell in Lebanon could transition from rainy to dry and semi-arid, with aridification in Lebanon claiming more land with every increasing increment of warming.
Each grid cell on the map is approximately 22 by 22 km or 484 square kilometers. Between 0.5°C and 2°C of warming, the map shows the number of dry, semi-arid grid cells doubling from 1 to 2, meaning as much as 968 square kilometers of the 10,50 square kilometer nation (9% of total land) could be semi-arid.
2.5°C and 3°C of warming are potential but avoidable, depending on the pace and scale of human greenhouse gas emissions. At 2.5°C of warming, the block of dry, semi-arid, cold climate (brown in the map key) in the Northwest of the country is projected to expand. Along with this increase in dryness, temperatures could become permanently hotter: The map shows the first dry, semi-arid, hot grid cells (dark brown in the map key) appearing in Lebanon, along the Northern border. All around Lebanon, more cells could transition into dry, hot climates.
At 3°C of warming, Lebanon could be a different place, permanently hot and dry in regions that were previously cool and rainy. Map projections show three dry, semi-arid, hot grid cells within Lebanon’s borders and an almost completely diminished buffer of cells separating Lebanon from the hot desert.
Because 2.5°C and 3°C are more distant thresholds of warming, these projections give us an impression of avoidable outcomes. Data like this can be as much a tool for avoiding harmful outcomes by slowing and stopping warming, as well as anticipating risk.
What could climate zone shift mean for Lebanon?
Lebanon’s unique geography and history are essential to considering its risk from climate zone shift. Thinking about climate zones and Lebanon’s vulnerabilities is the first step to understanding risks and making informed decisions about the future.
Here are a few guiding questions to start considering climate zone shift in Lebanon:
- Agriculture is the third most productive sector in the Lebanese economy and employs 8% of the labor force. What does it mean for crop suitability in Lebanon if large swathes of the country are consistently drier and hotter? How can the agricultural sector prepare for these changes?
- Lebanon shares borders with politically unstable countries. As these countries transition into dry, hot climates, and the borders with Lebanon become drier and hotter, how might populations move? How might this human migration affect Lebanon?
- Plants and animals adapt to specific local ranges in temperature and precipitation. As weather patterns in Lebanon transition away from the historic climate, how can ecosystems be protected?
Examining the range of possible outcomes for a climate impact in a place, putting that data in context, and looking for vulnerabilities is a framework you can apply to any place with any Probable Futures map. We offer maps of 30+ climate variables at warming scenarios ranging from 0.5 to 3°C of warming. We invite you to explore and think about what climate impacts could mean in the places you care about.