Geography of Peru

The eastern portions of Peru include the Amazon Basin or selva baja, a region that is larger in the north than in the south. Representing roughly 60% of Peru's national territory, this area includes the Amazon, Marañón, Huallaga and Ucayali Rivers.[14]

Almost 60% of the country's area is located within this region,[15] (700,000 km² or 270,000 sq mi) giving Peru the fourth largest area of tropical forest in the world after Brazil, Congo and Indonesia.[16]

The Andes shelter the very largest variety of climates in the country. The climate is semi-arid in the valleys and moist in higher elevations and towards the eastern flanks. Rainfall varies from 200 to 1,500 mm (7.9 to 59.1 in) per year. The monsoonal period starts in October and ends in April. The rainiest months are January through March where travel can be sometimes affected.

The western slopes are arid to semi-arid and receive rainfall only between January and March. Below the 2,500 m (8,202 ft) mark, the temperatures vary between 5 and 15 °C (41 and 59 °F) in the night versus 18 to 25 °C (64.4 to 77.0 °F) in the day.

Between 2,500 and 3,500 meters (8,202 and 11,483 ft), the temperatures vary from 0 to 12 °C (32.0 to 53.6 °F) in the night and from 15 to 25 °C (59 to 77 °F) during the day. At higher elevations from 3,500 to 4,500 meters (11,483 to 14,764 ft), the Puna ecoregion, the temperature varies from −10 to 8 °C (14.0 to 46.4 °F) during the night versus 15 °C (59 °F) during the day.

The northernmost regions of the Andes around Cajamarca and Piura regions have Páramo climates.

The Peruvian coast is a microclimatic region. The region is affected by the cold Humboldt Current, the El Niño Southern Oscillation, tropical latitude, and the Andes mountain range.

The central and southern coast consists mainly of a subtropical desert climate composed of sandy or rocky shores and inland cutting valleys. Days alternate between overcast skies with occasional fog in the winter and sunny skies with occasional haze in the summer, with the only precipitation being an occasional light-to-moderate drizzle that is known locally as garúa. These regions are usually characterized by mildly cold lows (14 °C or 57.2 °F) and also mild highs (29 °C or 84 °F). Temperatures rarely fall below 12 °C (53.6 °F) and do not go over 29 °C (84 °F). An exception is the southern coast, where it does get a bit warmer and drier for most of the year during daytime, and where it can also get much colder during winter nights (8 to 9 °C or 46.4 to 48.2 °F).

The northern coast, on the contrary, has a curious tropical-dry climate, generally referred to as tropical savanna. This region is a lot warmer and can be unbearable during summer months, where rainfall is also present. The region differs from the southern coast by the presence of shrubs, equatorial dry forests (Tumbes–Piura dry forests ecoregion), mangrove forests, tropical valleys near rivers such as the Chira and the Tumbes. The average temperature is 25 °C (77 °F).

The central and southern coast have a subtropical desert climate, despite this region being located in the tropics. The Humboldt Current, serving as one cause of climatic differentiation, is 7 to 8 °C (13 to 14 °F) colder than normal tropical seas at 14 to 19 °C (57 to 66 °F), thus preventing high tropical temperatures from appearing. Additionally, due to the height of the Andes cordillera, there is no passage of hot clouds from the Amazon to the coast, the climate is cooler than that of similar tropical latitudes. This can create a great deal of humidity and fog during winter months.

Moreover, the Andes mountains are very close to the coast, a geographic factor that prevents cumulus or cumulonimbus clouds from appearing. Therefore, a shade effect is created, causing very low annual rainfall in this region.[17]

Rainfall averages 5 mm (0.2 in) per year near the Chilean border to 200 mm (7.9 in) per year on the northern coast and nearer the Andes.

The central coast is composed of regions including La Libertad, Ancash and Lima, which have a spring-like climate for most of the year. Foggy and sunny days intermingle around the humid sand dunes during most of the year.

Most summers (February–April) have pleasant temperatures ranging from 19 to 21 °C (66 to 70 °F) during the night to about 28 to 29 °C (82 to 84 °F) during the daytime. Winters (August–October) are very humid, and range from 12 to 15 °C (54 to 59 °F) during the nights to around the 17 to 18 °C (63 to 64 °F) during the day. The spring (November–January) and autumn (May–July) months have a pleasant climate that ranges from 23 °C (73 °F) during the day to around 17 °C (63 °F) during the night. Moving inland into the Yunga valleys, the climate tends to be ~3 °C (5.4 °F) drier and warmer during any given month.

The southern coast, composed of the Ica, Arequipa, Moquegua and Tacna regions, has a drier and warmer climate during the day for all seasons, although colder in winter. There are regions famous for their sand dunes and impressive deserts that are, in part, caused by the drier and hotter climate. Temperatures in this region can reach up to 36 °C (97 °F) in the Nazca region while inland regions can fall to 8 or 9 °C (46 or 48 °F) during the winter months. During the day, temperatures rarely go below the 22 or 23 °C (72 or 73 °F) for all months of the year. This purports the idea that the southern coast has a more desert-like climate, although daily temperature variations exist as they do in other regions within tropical latitudes. Clear skies are often present in desert areas and, although less common, near the coastal cliffs as well, which are home to a variety of fish and marine mammals.

The northern coast consists of the eastern region of Lambayeque, the Piura Region and the Tumbes Region. They are characterized by having different climate and geography from the rest of the coast. Right between the 3-hour drive on the Sechura desert, which is located north of the Lambayeque Region and south of the Piura Region, is the evidence of climate change from the common subtropical desert found on the south to visible tropicalization effects of the tropical dry climate or tropical savanna. Examples of this are the tropical dry forests that begin to appear. They are composed of shrubs, thorny trees, carob trees, faique trees, guayacan trees, hualtaco trees, palo santo trees, ceibo trees and on the coast mangrove forests. It is also a biodiverse area where typical wildlife can be observed such as crocodiles, reptiles, iguanas, boas, pava aliblanca, anteater, bear, sloth (bearh) and many more.

This climatic change is caused by the presence of the warm El Niño Current during the summer months (December to April), the eventual El Niño Phenomenon and the passing of Amazon Jungles clouds due to mountain openings and lower altitudes of the Andes Chain. These are the causes for a climate change in a short two- or three-hour trajectory that is visible between the Lambayeque Region and the Sechura Province, where not only geography changes but a temperature rise of 6 °C (10.8 °F) or more depending on the month. It is directly off the shores of the Sechura Region where the cold Humboldt current and warm El Niño current meet, at about 5° to 6° south of the equator. From this point, warm temperatures are most common, and there are no true winters. Average temperatures range between 24.5–27 °C (76.1–80.6 °F).

Summer (December through March) is more humid and very hot, with average temperatures that vary from 25 °C (77 °F) during the night to around 34 °C (93.2 °F) during the day, although north of Lambayeque it can reach the 40 °C (104 °F). Winters (June–September) are cooler during the nights; around 16 °C (60.8 °F) during the night, to around 27 °C (80.6 °F) during the daytime.

There are protected areas in Tumbes and Piura such as the Coto de Caza El Angolo and the Cerros de Amotape National Park, with tropical dry forests that extend to the south of Ecuador. The eastern areas of Lambayeque also have tropical dry forests, where the Chaparrí Private Conservation Area is located in Chongoyape. These forests have the particularity of connecting with the Amazon basin through the Marañón pass (an area where there are also tropical dry forests).

Mangrove forests are located in four specific areas from Sechura to Tumbes. In these regions, the mangrove forests are at the ending strips of the Piura River in the Sechura Province (the southernmost mangroves in the Pacific Ocean). To the north, the ending strips of the Chira River, Tumbes River, and Zarumilla River also have mangrove forests that flow into the ocean.

Terrain: western coastal plain (costa), high and rugged Andes in center (sierra), eastern lowland jungle of Amazon Basin (selva).

Natural resources: copper, silver, gold, petroleum, timber, fish, iron ore, coal, phosphate, potash, hydropower.

As food production in Peru increases, farmers saturate the soil with nutrients with nitrogen and phosphorus bases. Oversaturation of nutrients leads to eutrophication in nearby water bodies, resulting in dead zones. Carbon emissions due to manufacturing and food processing leads to reduced air quality which contributes to the global warming that increases severity of natural disasters and acidifies the ocean, leading to mass bleaching in coral reefs, which in turn tends to destroy oceanic ecosystems.[21][22][23]