Participatory Plant Breeding. A method to adapt to climate change in low-input agriculture

4 2. Climate change and agriculture 2.1. Climate change: an overview Throughout our planet’s history, climate has always been changing. If we only focus on last 650.000 years, we realise that climate conditions on Earth have significantly changed many times. So far, there have been at least five major ice ages alternating with interglacial ages 2 . Climate changes during Holocene 3 have strongly influenced life conditions on Earth and the development of human civilization. They have shaped cultures and contributed to the invention of agriculture through the domestication of plants, as temperatures started raising and vegetation increased (Prentice, 2009). Therefore, climate change is not new. However, in recent times, a new type of climate change (CC, i.e. the one we are referring to in this work) has appeared. It has peculiar characteristics that make it different from all the other changes climate has undergone so far, due to its unprecedented rate of change and its anthropogenic nature (IPCC, 2014). Indeed, the main driver of CC is human activity (more than 95% of probability) in the form of greenhouse gas emissions, largely caused by economic and population growth on Earth, that sharply increased since 1750 (first industrial revolution) producing atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at the highest levels in the last 800,000 years (IPCC, 2014). Moreover, anthropogenic alterations in the atmospheric concentrations of aerosols, land cover and solar radiation have interfered with the energy balance of the climate system (IPCC, 2007). This process has caused a slowing-down of Earth surface’s cooling which, as a consequence, has increased global average temperatures and altered rainfall patterns since 1950s, with effects on physical and biological systems (IPCC, 2007). These changes in climate balance are already having and will further have significant consequences on different aspects and dimensions of life on Earth. 2 An ice age is a period of time (millions of years long) when Earth’s surface is covered by ice caps, that can be more or less extended. Ice ages are composed of glaciations, when glaciers advance, and interglacial periods, when glaciers retreat. During interglacial ages, instead, ice caps disappear from the surface of Earth. 3 The Holocene is the geologic time from about 10,000-7,000 years ago to the present. It began at the end of the last ice age and is characterized by the development of human civilizations.