{
  "slug": "solar-brightening-dimming",
  "title": "Brightening and Dimming: The Sky Is Not a Constant",
  "url": "https://solaranalytica.com/solar-brightening-dimming",
  "summary": "Two independent NASA instruments across 40 markets: 26 skies brightened over two decades and 14 dimmed, from Berlin at +6.8% to Jodhpur at -6.1%, with the instruments agreeing on direction in 29 of 40. Every percent of sky moves output almost one for one, so the trend can dwarf the warming penalty: Berlin's brightening is roughly eight times its modelled heat drift.",
  "license": "Free to use with attribution to Solar Analytica (solaranalytica.com). Underlying figures are named to their public sources below.",
  "csv": "https://solaranalytica.com/reports/solar-brightening-dimming/data.csv",
  "datePublished": "2026-04-23",
  "lastReviewed": "2026-04-23",
  "sources": [
    {
      "title": "NASA MERRA-2 reanalysis (market GHI series, 1994-2024)",
      "url": "https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/"
    },
    {
      "title": "NASA CERES (satellite surface irradiance record, 2000-2024)",
      "url": "https://ceres.larc.nasa.gov/"
    },
    {
      "title": "Wild: Global dimming and brightening, a review (JGR Atmospheres 2009)",
      "url": "https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2008JD011470"
    },
    {
      "title": "Solar Analytica methodology (yield baseline and data standards)",
      "url": "https://solaranalytica.com/methodology"
    }
  ],
  "figures": [
    {
      "id": "merra2-ghi-change",
      "title": "The MERRA-2 read. GHI change, 2014-2024 decade vs 1994-2003 decade",
      "unit": "%",
      "caption": "Instrument one: NASA MERRA-2 reanalysis. GHI change, 2014-2024 decade against 1994-2003. Across all 40 markets, 26 brightened and 14 dimmed; the set average is +0.4%.",
      "series": [
        {
          "label": "Berlin",
          "value": 6.8
        },
        {
          "label": "London",
          "value": 3.6
        },
        {
          "label": "Paris",
          "value": 3.5
        },
        {
          "label": "Santiago",
          "value": 3.5
        },
        {
          "label": "Athens",
          "value": 3.3
        },
        {
          "label": "Perth",
          "value": 1
        },
        {
          "label": "Riyadh",
          "value": -1.5
        },
        {
          "label": "Shanghai",
          "value": -2.6
        },
        {
          "label": "Jakarta",
          "value": -2.9
        },
        {
          "label": "Reykjavik",
          "value": -4.1
        },
        {
          "label": "Jodhpur",
          "value": -6.1
        }
      ]
    },
    {
      "id": "ceres-ghi-change",
      "title": "The CERES read. Same markets, independent satellite record",
      "unit": "%",
      "caption": "Instrument two: NASA CERES satellite radiometry, 2020-2024 against 2000-2009. The two instruments agree on the direction of change in 29 of 40 markets; Shanghai is the notable disagreement and is treated as unresolved.",
      "series": [
        {
          "label": "Berlin",
          "value": 4
        },
        {
          "label": "London",
          "value": 3.8
        },
        {
          "label": "Paris",
          "value": 3.3
        },
        {
          "label": "Santiago",
          "value": 6
        },
        {
          "label": "Athens",
          "value": 2.4
        },
        {
          "label": "Perth",
          "value": 0.7
        },
        {
          "label": "Riyadh",
          "value": -1.5
        },
        {
          "label": "Shanghai",
          "value": 0.5
        },
        {
          "label": "Jakarta",
          "value": -3.8
        },
        {
          "label": "Reykjavik",
          "value": -4.2
        },
        {
          "label": "Jodhpur",
          "value": -4
        }
      ]
    }
  ]
}