Climate of the Atlantic Ocean: Currents, Storms & Change

The Atlantic Ocean's climate is a dynamic engine driven by circulation, atmosphere, and now, human forcing.

Surface Currents (The Conveyor)

• Gulf Stream / North Atlantic Current: Warm, salty, fast — carries tropical heat to NW Europe (mild winters).
• Canary Current: Cold, eastern boundary — upwelling, fisheries (NW Africa).
• Benguela Current: Cold, eastern boundary (SW Africa) — intense upwelling, diamonds, fisheries.
• Brazil Current: Warm, western boundary (S. Atlantic).
• South Equatorial / North Brazil Current: Tropical gyre circulation.
• Labrador Current: Cold, Arctic → Grand Banks — icebergs, fog, cod (historically).

North Atlantic Oscillation (NAO)

• Positive NAO: Strong Icelandic Low + Azores High → strong westerlies → **mild/wet N. Europe, cold/dry E. US/Canada**.
• Negative NAO: Weak pressure gradient → **cold/snowy Europe, mild/wet E. US**.
• Major driver of winter variability.

Hurricanes (Tropical Cyclones)

• **Main Development Region:** Tropical N. Atlantic (June–Nov, peak Sept).
• Fueled by SST >26.5°C, low shear, moisture.
• Tracks: Caribbean → Gulf / US East Coast / Bermuda / Azores.
• **Climate Change:** More intense (Cat 4/5), slower, wetter, rapid intensification.

Climate Change Impacts

• Warming: SST rising; marine heatwaves; species shifts.
• AMOC Slowdown: Atlantic Meridional Overturning Circulation weakening (freshwater from Greenland melt) → could cool NW Europe, raise US sea level, shift rain belts.
• Sea Level Rise: Thermal expansion + ice melt → accelerating (3–4 mm/yr globally; higher US East/Gulf coasts).
• Acidification: CO₂ uptake → lower pH → shellfish/coral stress.
• Deoxygenation: Warmer water holds less O₂; stratification reduces mixing.

The Atlantic is a **climate regulator** now under profound anthropogenic stress.