September 2023 Notes

Olive trees have been cultivated around the Mediterranean for thousands of years, with Spain alone producing half of the world’s supply of olive oil, but wildfires and soaring summer temperatures mean the future of this ancient industry is looking increasingly uncertain.

Global production is expected to fall to 2.4m tonnes according to the International Olive Council, less than last year’s harvest and well short of global demand of about 3m tonnes, after drought and heatwaves of more than 40 degrees hit production in Spain.

Extreme weather in other important growing regions including Greece, Italy and Portugal as well as Turkey and Morocco has added to the crisis.

Italy’s growers have also been affected by the bacterial disease nicknamed “olive ebola” – Xylella fastidiosa – which has killed 6m trees in recent years.

Mediterranean agriculture

“Thessaly has been set back years. People are talking about going hungry. In this soil, I don’t think you will be able to grow anything properly for three to four years. I’ve found dead fish in the soil. The earth is sick.”

“One bad harvest makes the next difficult, even in normal circumstances” he said. “But right now, the word ‘normal’ is no longer in our vocabulary.”

The influence of regional climate change (CC) on agricultural production variance in the Mediterranean region has been discussed based on the assessment of the last decade. Most of the Mediterranean region has experienced frequent natural disasters, expanding population, increase in temperature, and increase in the surface of the Mediterranean Sea.

Furthermore, the temperature in the Mediterranean area is rising 25% faster than the rest of the globe, and in the summer, it is warming 40% faster than the global average. Climate change can alter the food supply, restrict access to food, and degrade food quality.

Introduction

The Mediterranean is the consequence of rifting, spreading, subduction, and colliding plates and microplates dating back to the Mesozoic.

To better understand the consequences of these changes, ecological field tests have shown that planting more species increases productivity and stability. (Ed. Was there greater crop diversity in the past?)

Even though precipitation variability is not the only thing that matters in agriculture, it is crucial as 60–95% of the farming land in the developing world is done so by rainfed agriculture. Statistically, it was found that there is a drop of 0.5% for every percentage point decrease in rainfall.

The average annual temperature in the basin is about 1.4 °C, higher than in the late 1800s.

Since 1950, heat waves have been happening more often, and droughts are happening more often and worsening.

In the last three decades, the surface of the Mediterranean Sea has warmed by about 0.4 °C.

Over the last 20 years, the sea level has risen by about 3 cm per decade.

The Mediterranean region is expected to warm up 25% faster than the rest of the world in the future, and the summer will warm up 40% faster than the global average. Even if the world warms by the “Paris-compliant” 1.5 °C, regional daytime highs are likely to rise by 2.2 °C.

A 2 °C rise in the average temperature of the atmosphere around the world will almost certainly cause a 10–15% drop in summer rain in southern France, northwest Spain, and the Balkans, and a 30% drop in Turkey and Portugal.

Scenarios in which Southern Europe’s temperatures rise by 2–4 °C in the 2080s would lead to a 30 per cent drop in precipitation (especially in the spring and summer months) and the end of the frost season in the Balkans.

For every one degree of global warming, average rainfall will drop by about 4% in most regions, especially in the south. This variation will make dry spells 7% longer. Heavy rain is likely to get 10–20% stronger, except in the summer. (Ed. Check these figures, esp. 1% increase temperature leads to 4% increase precipitation; seems low compared to other figures given here.)

(Ed. Water stress esp. likely in Libya as freshwater withdrawls increase substantially.)

Extreme rainfall increases the likelihood of floods. This increase is partially caused by CC, which reveals new challenges that have little to do with weather, such as the expansion of cities and the poor management of stormwater.

The Mediterranean countries have about 877 million ha of land, with agriculture accounting for about 28% of the total land area. The share of agricultural land varies significantly across the country, ranging from 4% in Egypt to nearly 76% in Syria.

There are a lot of different farm structures, agro-management practices in the agriculture sector, and significant differences in environmental conditions. This means that agricultural inputs (like nutrients, pesticides, and irrigation water) and outputs vary a lot (e.g., crop yields). Only 8% of the agricultural land in the Mediterranean is irrigated (Ed. uncertain as many areas not measured.).

Effects of Climate Change on Agriculture in the Mediterranean Region

The five regions (MCRs) constitute 2% of the Earth’s surface area, 20% of the world’s plant species, and 5% of the world’s population.

Effects of Water

• Drought stress significantly impacts agricultural productivity.
• Annual crops, such as cereals, are susceptible to progressive water scarcity during the blossoming and grain-filling phases in rainfed parts of the MCRs and semi-arid tropics, resulting in “terminal drought stress”.
• The harvest index, or the proportion of aboveground biomass allocated to grain, decreases during terminal drought circumstances.
• The quantity of water available for irrigation in most irrigated MCRs is decreasing due to recurring drought and intense competition for water resources among agriculture, industry, and urban areas.
• Higher temperatures increase evapotranspiration and agricultural irrigation needs.
• Water scarcity impacts the reproductive and seed/fruit development phases more than the vegetative or maturity stages.
• Water shortages throughout the blooming and fruit development periods result in a more significant decline in fruit yield than shortfalls towards fruit maturity.
• MCR temperatures are anticipated to climb by 2–4 °C by the mid-twenty-first century.
• High temperatures can affect various physiological and metabolic processes in plants, affecting their development, growth, and production. Higher temperatures related to CC have been shown to impair agricultural output and quality.
• Even mild temperature increases hasten plant growth, shortening the growing season and decreasing plant biomass. Consequently, changes in phenological dates will change the crop season duration and water requirements.
• Temperatures and evapotranspiration will rise in areas with warm spring and summer seasons (severe scenario, up to 4 °C). (Ed. Check affects under different scenarios).
• Warmer weather (moderate scenario, up to 2 °C) may benefit agricultural production when temperature restricts the duration of the growing season. (Ed. Check affects under different scenarios).

Sustainability and the Five Domains

• Annual mean temperatures are currently 1.4 °C above levels from the late nineteenth century.
• Since 1950 heat waves and severe droughts have increased in frequency.
• Growing salinity variations may impact regional changes in river discharge along the Mediterranean coastlines, leading to a substantial land shift in the basin’s eastern regions. Even though Mediterranean circulation patterns can be altered, global sea-level rise will dominate future Mediterranean Sea-level change.
• Along the Mediterranean coast, increased CO2 absorption by the seas and acidification of 0.15 to 0.41 pH units are anticipated to induce significant impacts.
• Due to the possibility of substantial yield gains in many southern and eastern land systems, agricultural land management is increasing, primarily via more excellent irrigation, with ramifications for water resources, biodiversity, and landscape functioning.
• Despite local advancements in wastewater treatment, air and water pollution continue to grow due to urbanization, traffic, and other factors.
• Political conflicts have a substantial environmental effect, and migratory pressure continues to affect economies with limited resources, making it more difficult for them to adapt to environmental changes.
• Water resources
  • Most likely, the water in lakes and reservoirs will go down. Stream flow patterns are likely to change, with high spring flows from melting snow ending earlier, summer low flows getting more robust, and winter flows getting more significant and unpredictable.
  • The amount of water per person in the Mediterranean, which is already very low, will drop to less than 500 m3 per year.
  • Extreme rainfall events will increase the likelihood of flooding, exacerbated by CC and non-climatic variables such as increased urbanization and inadequate stormwater management systems.
• Managed Ecosystems
  • The diversity and long-term viability of Mediterranean land ecosystems may be most jeopardized by increased aridity brought on by decreased precipitation and rising temperatures.
  • Greater fire danger, longer fire seasons, and more catastrophic wildfires are predicted due to changing climate, increased heat waves, dryness, and land use.
• Food Production and Security
  • Crop illnesses, yield reductions, and more significant production variability may all occur due to extreme weather events like heat waves, cold snaps, or heavy rainfall during critical phenological stages. Many winter and spring crops, particularly in the southern Mediterranean, are expected to be affected by CC.
  • Olive production will be harmed due to rising irrigation demands due to CC. Local and regional discrepancies will arise, while the influence on aggregate production is not anticipated to be significant.
  • It is anticipated that the phenological cycle of grapevines would shift toward shorter length and earlier blooming, accompanied by increased vulnerability to severe events and water stress. These circumstances may also affect the quality of grapes.
  • Flowering and chilling accumulation are anticipated to influence fruit tree output.
  • Reduced water, such as in tomatoes, will be the primary factor restricting crop yields.
  • Water-saving measures might be devised to enhance crops’ quality and nutritional value while maintaining appropriate output levels.
  • Due to CO2-fertilization effects, yield improvements may occur in some crops, which might boost water usage efficiency and biomass output, even though the intricate interactions among the numerous components and the present knowledge gaps suggest significant uncertainty. In addition, these yields are anticipated to decline in quality (e.g., a fall in the protein content of cereals).
  • In some regions, sea-level rise and ground subsidence may severely diminish agricultural land. The consequences of sea-level rise will impose more restrictions on agricultural land, notably in the Nile Delta and other productive delta regions.
• Human Health
  • Heat, cold, drought, and storms (direct factors) as well as food quality, food availability, pollution, and the affect CC has on social and cultural issues, and the subsequent impact on human health, are all substantial.
• Human Security
  • More than a third of the inhabitants in the Mediterranean Basin live within walking distance of the sea.
  • By 2050, half of the 20 cities with the most significant yearly increase in damages will be in the Mediterranean, according to lower sea-level rise scenarios and current adaptation efforts.
  • As sea levels rise, saltwater intrusion will become more prevalent in coastal areas.

Crop Yield Security in Mediterranean Region

Global agricultural output is increased through technological improvements, new seed and fertilizer variations, and improved farming techniques. Simultaneously, climatic variations, mainly the frequency of extreme weather events and shifting seasons, as well as regional water and energy limitations, are driving yield declines and weakening food security. To make matters worse, the frequency and severity of severe weather events have been predicted to rise due to human-caused global CC.

Crop Production Variation in Mediterranean Region

Agricultural production has a significant spatial variation in the Mediterranean region. (Ed. Crops with variation include wheat, barley and rice)

Climate Smart Approach

Climate change is expected to alter agricultural production systems globally, putting billions of people’s livelihoods and food security at risk. Agricultural production would be negatively impacted by rising temperatures, shifting precipitation patterns, and more frequent and severe floods and droughts. Some agricultural output losses might be as high as 60% due to CC, depending on the crop type, location and weather patterns. Nearly one-third of yield variation is attributed to CC, which might significantly impact agricultural production and food security. An estimated 19–29% of GHG emissions are attributed to the agricultural food system, which is vulnerable to global CC and the second most significant contributor to its causes.

Agricultural management, such as sowing dates, cropping practices, and land usage must be adjusted to account for CC.